m_clalloc() was improperly assuming that an mcl malloc would always succeed
[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 $
446c0d3a 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.10 2005/02/04 01:06:05 joerg 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>
8ca15ec8 43#include <sys/resident.h>
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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
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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 */
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79static void die(void);
80static void digest_dynamic(Obj_Entry *);
8ca15ec8 81static const char *_getenv_ld(const char *id);
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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 */
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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 */
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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 */
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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;
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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 */
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151static const char *ld_ary[LD_ARY_CACHE];
152static int ld_index;
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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;
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263 Objlist initlist;
264
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265 ld_index = 0; /* don't use old env cache in case we are resident */
266
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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
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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 }
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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) {
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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");
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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
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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
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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
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406resident_skip1:
407
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408 if (ld_tracing) { /* We're done */
409 trace_loaded_objects(obj_main);
410 exit(0);
411 }
412
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413 if (ld_resident) /* XXX clean this up! */
414 goto resident_skip2;
415
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416 if (getenv("LD_DUMP_REL_PRE") != NULL) {
417 dump_relocations(obj_main);
418 exit (0);
419 }
420
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421 if (relocate_objects(obj_main,
422 ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
423 die();
984263bc 424
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425 dbg("doing copy relocations");
426 if (do_copy_relocations(obj_main) == -1)
427 die();
1c76efe5 428
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429resident_skip2:
430
8ca15ec8 431 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
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432 if (exec_sys_unregister(-1) < 0) {
433 dbg("exec_sys_unregister failed %d\n", errno);
434 exit(errno);
435 }
436 dbg("exec_sys_unregister success\n");
437 exit(0);
438 }
984263bc 439
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440 if (getenv("LD_DUMP_REL_POST") != NULL) {
441 dump_relocations(obj_main);
442 exit (0);
443 }
444
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445 dbg("initializing key program variables");
446 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
447 set_program_var("environ", env);
448
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449 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
450 extern void resident_start(void);
451 ld_resident = 1;
452 if (exec_sys_register(resident_start) < 0) {
453 dbg("exec_sys_register failed %d\n", errno);
454 exit(errno);
455 }
456 dbg("exec_sys_register success\n");
457 exit(0);
458 }
459
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460 dbg("initializing thread locks");
461 lockdflt_init(&lockinfo);
462 lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
463
464 /* Make a list of init functions to call. */
465 objlist_init(&initlist);
466 initlist_add_objects(obj_list, preload_tail, &initlist);
467
468 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
469
470 objlist_call_init(&initlist);
471 wlock_acquire();
472 objlist_clear(&initlist);
473 wlock_release();
474
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475
476
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477 dbg("transferring control to program entry point = %p", obj_main->entry);
478
479 /* Return the exit procedure and the program entry point. */
480 *exit_proc = rtld_exit;
481 *objp = obj_main;
482 return (func_ptr_type) obj_main->entry;
483}
484
485Elf_Addr
486_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
487{
488 const Elf_Rel *rel;
489 const Elf_Sym *def;
490 const Obj_Entry *defobj;
491 Elf_Addr *where;
492 Elf_Addr target;
493
494 rlock_acquire();
495 if (obj->pltrel)
496 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
497 else
498 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
499
500 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
501 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
502 if (def == NULL)
503 die();
504
505 target = (Elf_Addr)(defobj->relocbase + def->st_value);
506
507 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
508 defobj->strtab + def->st_name, basename(obj->path),
509 (void *)target, basename(defobj->path));
510
511 reloc_jmpslot(where, target);
512 rlock_release();
513 return target;
514}
515
516/*
517 * Error reporting function. Use it like printf. If formats the message
518 * into a buffer, and sets things up so that the next call to dlerror()
519 * will return the message.
520 */
521void
522_rtld_error(const char *fmt, ...)
523{
524 static char buf[512];
525 va_list ap;
526
527 va_start(ap, fmt);
528 vsnprintf(buf, sizeof buf, fmt, ap);
529 error_message = buf;
530 va_end(ap);
531}
532
533/*
534 * Return a dynamically-allocated copy of the current error message, if any.
535 */
536static char *
537errmsg_save(void)
538{
539 return error_message == NULL ? NULL : xstrdup(error_message);
540}
541
542/*
543 * Restore the current error message from a copy which was previously saved
544 * by errmsg_save(). The copy is freed.
545 */
546static void
547errmsg_restore(char *saved_msg)
548{
549 if (saved_msg == NULL)
550 error_message = NULL;
551 else {
552 _rtld_error("%s", saved_msg);
553 free(saved_msg);
554 }
555}
556
1c76efe5 557const char *
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558basename(const char *name)
559{
560 const char *p = strrchr(name, '/');
561 return p != NULL ? p + 1 : name;
562}
563
564static void
565die(void)
566{
567 const char *msg = dlerror();
568
569 if (msg == NULL)
570 msg = "Fatal error";
571 errx(1, "%s", msg);
572}
573
574/*
575 * Process a shared object's DYNAMIC section, and save the important
576 * information in its Obj_Entry structure.
577 */
578static void
579digest_dynamic(Obj_Entry *obj)
580{
581 const Elf_Dyn *dynp;
582 Needed_Entry **needed_tail = &obj->needed;
583 const Elf_Dyn *dyn_rpath = NULL;
584 int plttype = DT_REL;
585
586 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
587 switch (dynp->d_tag) {
588
589 case DT_REL:
590 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
591 break;
592
593 case DT_RELSZ:
594 obj->relsize = dynp->d_un.d_val;
595 break;
596
597 case DT_RELENT:
598 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
599 break;
600
601 case DT_JMPREL:
602 obj->pltrel = (const Elf_Rel *)
603 (obj->relocbase + dynp->d_un.d_ptr);
604 break;
605
606 case DT_PLTRELSZ:
607 obj->pltrelsize = dynp->d_un.d_val;
608 break;
609
610 case DT_RELA:
611 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
612 break;
613
614 case DT_RELASZ:
615 obj->relasize = dynp->d_un.d_val;
616 break;
617
618 case DT_RELAENT:
619 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
620 break;
621
622 case DT_PLTREL:
623 plttype = dynp->d_un.d_val;
624 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
625 break;
626
627 case DT_SYMTAB:
628 obj->symtab = (const Elf_Sym *)
629 (obj->relocbase + dynp->d_un.d_ptr);
630 break;
631
632 case DT_SYMENT:
633 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
634 break;
635
636 case DT_STRTAB:
637 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
638 break;
639
640 case DT_STRSZ:
641 obj->strsize = dynp->d_un.d_val;
642 break;
643
644 case DT_HASH:
645 {
646 const Elf_Addr *hashtab = (const Elf_Addr *)
647 (obj->relocbase + dynp->d_un.d_ptr);
648 obj->nbuckets = hashtab[0];
649 obj->nchains = hashtab[1];
650 obj->buckets = hashtab + 2;
651 obj->chains = obj->buckets + obj->nbuckets;
652 }
653 break;
654
655 case DT_NEEDED:
656 if (!obj->rtld) {
657 Needed_Entry *nep = NEW(Needed_Entry);
658 nep->name = dynp->d_un.d_val;
659 nep->obj = NULL;
660 nep->next = NULL;
661
662 *needed_tail = nep;
663 needed_tail = &nep->next;
664 }
665 break;
666
667 case DT_PLTGOT:
668 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
669 break;
670
671 case DT_TEXTREL:
672 obj->textrel = true;
673 break;
674
675 case DT_SYMBOLIC:
676 obj->symbolic = true;
677 break;
678
679 case DT_RPATH:
680 /*
681 * We have to wait until later to process this, because we
682 * might not have gotten the address of the string table yet.
683 */
684 dyn_rpath = dynp;
685 break;
686
687 case DT_SONAME:
688 /* Not used by the dynamic linker. */
689 break;
690
691 case DT_INIT:
692 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
693 break;
694
695 case DT_FINI:
696 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
697 break;
698
699 case DT_DEBUG:
700 /* XXX - not implemented yet */
701 dbg("Filling in DT_DEBUG entry");
702 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
703 break;
704
705 default:
706 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
707 break;
708 }
709 }
710
711 obj->traced = false;
712
713 if (plttype == DT_RELA) {
714 obj->pltrela = (const Elf_Rela *) obj->pltrel;
715 obj->pltrel = NULL;
716 obj->pltrelasize = obj->pltrelsize;
717 obj->pltrelsize = 0;
718 }
719
720 if (dyn_rpath != NULL)
721 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
722}
723
724/*
725 * Process a shared object's program header. This is used only for the
726 * main program, when the kernel has already loaded the main program
727 * into memory before calling the dynamic linker. It creates and
728 * returns an Obj_Entry structure.
729 */
730static Obj_Entry *
731digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
732{
733 Obj_Entry *obj;
734 const Elf_Phdr *phlimit = phdr + phnum;
735 const Elf_Phdr *ph;
736 int nsegs = 0;
737
738 obj = obj_new();
739 for (ph = phdr; ph < phlimit; ph++) {
740 switch (ph->p_type) {
741
742 case PT_PHDR:
743 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
744 _rtld_error("%s: invalid PT_PHDR", path);
745 return NULL;
746 }
747 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
748 obj->phsize = ph->p_memsz;
749 break;
750
751 case PT_INTERP:
752 obj->interp = (const char *) ph->p_vaddr;
753 break;
754
755 case PT_LOAD:
756 if (nsegs == 0) { /* First load segment */
757 obj->vaddrbase = trunc_page(ph->p_vaddr);
758 obj->mapbase = (caddr_t) obj->vaddrbase;
759 obj->relocbase = obj->mapbase - obj->vaddrbase;
760 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
761 obj->vaddrbase;
762 } else { /* Last load segment */
763 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
764 obj->vaddrbase;
765 }
766 nsegs++;
767 break;
768
769 case PT_DYNAMIC:
770 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
771 break;
772 }
773 }
774 if (nsegs < 1) {
775 _rtld_error("%s: too few PT_LOAD segments", path);
776 return NULL;
777 }
778
779 obj->entry = entry;
780 return obj;
781}
782
783static Obj_Entry *
784dlcheck(void *handle)
785{
786 Obj_Entry *obj;
787
788 for (obj = obj_list; obj != NULL; obj = obj->next)
789 if (obj == (Obj_Entry *) handle)
790 break;
791
792 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
793 _rtld_error("Invalid shared object handle %p", handle);
794 return NULL;
795 }
796 return obj;
797}
798
799/*
800 * If the given object is already in the donelist, return true. Otherwise
801 * add the object to the list and return false.
802 */
803static bool
804donelist_check(DoneList *dlp, const Obj_Entry *obj)
805{
806 unsigned int i;
807
808 for (i = 0; i < dlp->num_used; i++)
809 if (dlp->objs[i] == obj)
810 return true;
811 /*
812 * Our donelist allocation should always be sufficient. But if
813 * our threads locking isn't working properly, more shared objects
814 * could have been loaded since we allocated the list. That should
815 * never happen, but we'll handle it properly just in case it does.
816 */
817 if (dlp->num_used < dlp->num_alloc)
818 dlp->objs[dlp->num_used++] = obj;
819 return false;
820}
821
822/*
823 * Hash function for symbol table lookup. Don't even think about changing
824 * this. It is specified by the System V ABI.
825 */
826unsigned long
827elf_hash(const char *name)
828{
829 const unsigned char *p = (const unsigned char *) name;
830 unsigned long h = 0;
831 unsigned long g;
832
833 while (*p != '\0') {
834 h = (h << 4) + *p++;
835 if ((g = h & 0xf0000000) != 0)
836 h ^= g >> 24;
837 h &= ~g;
838 }
839 return h;
840}
841
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
984263bc
MD
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
446c0d3a
JS
879 if(refobj != NULL && refobj->path != NULL) {
880 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
881 name, basename(refobj->path));
882 } else {
883 _rtld_error("Shared object \"%s\" not found", name);
884 }
984263bc
MD
885 return NULL;
886}
887
888/*
889 * Given a symbol number in a referencing object, find the corresponding
890 * definition of the symbol. Returns a pointer to the symbol, or NULL if
891 * no definition was found. Returns a pointer to the Obj_Entry of the
892 * defining object via the reference parameter DEFOBJ_OUT.
893 */
894const Elf_Sym *
895find_symdef(unsigned long symnum, const Obj_Entry *refobj,
896 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
897{
898 const Elf_Sym *ref;
899 const Elf_Sym *def;
900 const Obj_Entry *defobj;
901 const char *name;
902 unsigned long hash;
903
904 /*
905 * If we have already found this symbol, get the information from
906 * the cache.
907 */
908 if (symnum >= refobj->nchains)
909 return NULL; /* Bad object */
910 if (cache != NULL && cache[symnum].sym != NULL) {
911 *defobj_out = cache[symnum].obj;
912 return cache[symnum].sym;
913 }
914
915 ref = refobj->symtab + symnum;
916 name = refobj->strtab + ref->st_name;
917 hash = elf_hash(name);
918 defobj = NULL;
919
920 def = symlook_default(name, hash, refobj, &defobj, in_plt);
921
922 /*
923 * If we found no definition and the reference is weak, treat the
924 * symbol as having the value zero.
925 */
926 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
927 def = &sym_zero;
928 defobj = obj_main;
929 }
930
931 if (def != NULL) {
932 *defobj_out = defobj;
933 /* Record the information in the cache to avoid subsequent lookups. */
934 if (cache != NULL) {
935 cache[symnum].sym = def;
936 cache[symnum].obj = defobj;
937 }
938 } else
939 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
940 return def;
941}
942
943/*
944 * Return the search path from the ldconfig hints file, reading it if
945 * necessary. Returns NULL if there are problems with the hints file,
946 * or if the search path there is empty.
947 */
948static const char *
949gethints(void)
950{
951 static char *hints;
952
953 if (hints == NULL) {
954 int fd;
955 struct elfhints_hdr hdr;
956 char *p;
957
958 /* Keep from trying again in case the hints file is bad. */
959 hints = "";
960
961 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
962 return NULL;
963 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
964 hdr.magic != ELFHINTS_MAGIC ||
965 hdr.version != 1) {
966 close(fd);
967 return NULL;
968 }
969 p = xmalloc(hdr.dirlistlen + 1);
970 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
971 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
972 free(p);
973 close(fd);
974 return NULL;
975 }
976 hints = p;
977 close(fd);
978 }
979 return hints[0] != '\0' ? hints : NULL;
980}
981
982static void
983init_dag(Obj_Entry *root)
984{
985 DoneList donelist;
986
987 donelist_init(&donelist);
988 init_dag1(root, root, &donelist);
989}
990
991static void
992init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
993{
994 const Needed_Entry *needed;
995
996 if (donelist_check(dlp, obj))
997 return;
998 objlist_push_tail(&obj->dldags, root);
999 objlist_push_tail(&root->dagmembers, obj);
1000 for (needed = obj->needed; needed != NULL; needed = needed->next)
1001 if (needed->obj != NULL)
1002 init_dag1(root, needed->obj, dlp);
1003}
1004
1005/*
1006 * Initialize the dynamic linker. The argument is the address at which
1007 * the dynamic linker has been mapped into memory. The primary task of
1008 * this function is to relocate the dynamic linker.
1009 */
1010static void
1011init_rtld(caddr_t mapbase)
1012{
1013 /*
1014 * Conjure up an Obj_Entry structure for the dynamic linker.
1015 *
1016 * The "path" member is supposed to be dynamically-allocated, but we
1017 * aren't yet initialized sufficiently to do that. Below we will
1018 * replace the static version with a dynamically-allocated copy.
1019 */
1020 obj_rtld.path = PATH_RTLD;
1021 obj_rtld.rtld = true;
1022 obj_rtld.mapbase = mapbase;
1023#ifdef PIC
1024 obj_rtld.relocbase = mapbase;
1025#endif
1026 if (&_DYNAMIC != 0) {
1027 obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1028 digest_dynamic(&obj_rtld);
1029 assert(obj_rtld.needed == NULL);
1030 assert(!obj_rtld.textrel);
1031
1032 /*
1033 * Temporarily put the dynamic linker entry into the object list, so
1034 * that symbols can be found.
1035 */
1036 obj_list = &obj_rtld;
1037 obj_tail = &obj_rtld.next;
1038 obj_count = 1;
1039
1040 relocate_objects(&obj_rtld, true);
1041 }
1042
1043 /* Make the object list empty again. */
1044 obj_list = NULL;
1045 obj_tail = &obj_list;
1046 obj_count = 0;
1047
1048 /* Replace the path with a dynamically allocated copy. */
1049 obj_rtld.path = xstrdup(obj_rtld.path);
1050
1051 r_debug.r_brk = r_debug_state;
1052 r_debug.r_state = RT_CONSISTENT;
1053}
1054
1055/*
1056 * Add the init functions from a needed object list (and its recursive
1057 * needed objects) to "list". This is not used directly; it is a helper
1058 * function for initlist_add_objects(). The write lock must be held
1059 * when this function is called.
1060 */
1061static void
1062initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1063{
1064 /* Recursively process the successor needed objects. */
1065 if (needed->next != NULL)
1066 initlist_add_neededs(needed->next, list);
1067
1068 /* Process the current needed object. */
1069 if (needed->obj != NULL)
1070 initlist_add_objects(needed->obj, &needed->obj->next, list);
1071}
1072
1073/*
1074 * Scan all of the DAGs rooted in the range of objects from "obj" to
1075 * "tail" and add their init functions to "list". This recurses over
1076 * the DAGs and ensure the proper init ordering such that each object's
1077 * needed libraries are initialized before the object itself. At the
1078 * same time, this function adds the objects to the global finalization
1079 * list "list_fini" in the opposite order. The write lock must be
1080 * held when this function is called.
1081 */
1082static void
1083initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1084{
1085 if (obj->init_done)
1086 return;
1087 obj->init_done = true;
1088
1089 /* Recursively process the successor objects. */
1090 if (&obj->next != tail)
1091 initlist_add_objects(obj->next, tail, list);
1092
1093 /* Recursively process the needed objects. */
1094 if (obj->needed != NULL)
1095 initlist_add_neededs(obj->needed, list);
1096
1097 /* Add the object to the init list. */
1098 if (obj->init != NULL)
1099 objlist_push_tail(list, obj);
1100
1101 /* Add the object to the global fini list in the reverse order. */
1102 if (obj->fini != NULL)
1103 objlist_push_head(&list_fini, obj);
1104}
1105
1106static bool
1107is_exported(const Elf_Sym *def)
1108{
1109 func_ptr_type value;
1110 const func_ptr_type *p;
1111
1112 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1113 for (p = exports; *p != NULL; p++)
1114 if (*p == value)
1115 return true;
1116 return false;
1117}
1118
1119/*
1120 * Given a shared object, traverse its list of needed objects, and load
1121 * each of them. Returns 0 on success. Generates an error message and
1122 * returns -1 on failure.
1123 */
1124static int
1125load_needed_objects(Obj_Entry *first)
1126{
1127 Obj_Entry *obj;
1128
1129 for (obj = first; obj != NULL; obj = obj->next) {
1130 Needed_Entry *needed;
1131
1132 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1133 const char *name = obj->strtab + needed->name;
1134 char *path = find_library(name, obj);
1135
1136 needed->obj = NULL;
1137 if (path == NULL && !ld_tracing)
1138 return -1;
1139
1140 if (path) {
1141 needed->obj = load_object(path);
1142 if (needed->obj == NULL && !ld_tracing)
1143 return -1; /* XXX - cleanup */
1144 }
1145 }
1146 }
1147
1148 return 0;
1149}
1150
1151static int
1152load_preload_objects(void)
1153{
1154 char *p = ld_preload;
1155 static const char delim[] = " \t:;";
1156
1157 if (p == NULL)
1158 return NULL;
1159
1160 p += strspn(p, delim);
1161 while (*p != '\0') {
1162 size_t len = strcspn(p, delim);
1163 char *path;
1164 char savech;
1165
1166 savech = p[len];
1167 p[len] = '\0';
1168 if ((path = find_library(p, NULL)) == NULL)
1169 return -1;
1170 if (load_object(path) == NULL)
1171 return -1; /* XXX - cleanup */
1172 p[len] = savech;
1173 p += len;
1174 p += strspn(p, delim);
1175 }
1176 return 0;
1177}
1178
1179/*
1180 * Load a shared object into memory, if it is not already loaded. The
1181 * argument must be a string allocated on the heap. This function assumes
1182 * responsibility for freeing it when necessary.
1183 *
1184 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1185 * on failure.
1186 */
1187static Obj_Entry *
1188load_object(char *path)
1189{
1190 Obj_Entry *obj;
1191 int fd = -1;
1192 struct stat sb;
1193
1194 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1195 if (strcmp(obj->path, path) == 0)
1196 break;
1197
1198 /*
1199 * If we didn't find a match by pathname, open the file and check
1200 * again by device and inode. This avoids false mismatches caused
1201 * by multiple links or ".." in pathnames.
1202 *
1203 * To avoid a race, we open the file and use fstat() rather than
1204 * using stat().
1205 */
1206 if (obj == NULL) {
1207 if ((fd = open(path, O_RDONLY)) == -1) {
1208 _rtld_error("Cannot open \"%s\"", path);
1209 return NULL;
1210 }
1211 if (fstat(fd, &sb) == -1) {
1212 _rtld_error("Cannot fstat \"%s\"", path);
1213 close(fd);
1214 return NULL;
1215 }
1216 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1217 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
1218 close(fd);
1219 break;
1220 }
1221 }
1222 }
1223
1224 if (obj == NULL) { /* First use of this object, so we must map it in */
1225 dbg("loading \"%s\"", path);
1226 obj = map_object(fd, path, &sb);
1227 close(fd);
1228 if (obj == NULL) {
1229 free(path);
1230 return NULL;
1231 }
1232
1233 obj->path = path;
1234 digest_dynamic(obj);
1235
1236 *obj_tail = obj;
1237 obj_tail = &obj->next;
1238 obj_count++;
1239 linkmap_add(obj); /* for GDB & dlinfo() */
1240
1241 dbg(" %p .. %p: %s", obj->mapbase,
1242 obj->mapbase + obj->mapsize - 1, obj->path);
1243 if (obj->textrel)
1244 dbg(" WARNING: %s has impure text", obj->path);
1245 } else
1246 free(path);
1247
1248 obj->refcount++;
1249 return obj;
1250}
1251
1252/*
1253 * Check for locking violations and die if one is found.
1254 */
1255static void
1256lock_check(void)
1257{
1258 int rcount, wcount;
1259
1260 rcount = lockinfo.rcount;
1261 wcount = lockinfo.wcount;
1262 assert(rcount >= 0);
1263 assert(wcount >= 0);
1264 if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1265 _rtld_error("Application locking error: %d readers and %d writers"
1266 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1267 rcount, wcount);
1268 die();
1269 }
1270}
1271
1272static Obj_Entry *
1273obj_from_addr(const void *addr)
1274{
1275 unsigned long endhash;
1276 Obj_Entry *obj;
1277
1278 endhash = elf_hash(END_SYM);
1279 for (obj = obj_list; obj != NULL; obj = obj->next) {
1280 const Elf_Sym *endsym;
1281
1282 if (addr < (void *) obj->mapbase)
1283 continue;
1284 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL)
1285 continue; /* No "end" symbol?! */
1286 if (addr < (void *) (obj->relocbase + endsym->st_value))
1287 return obj;
1288 }
1289 return NULL;
1290}
1291
1292/*
1293 * Call the finalization functions for each of the objects in "list"
1294 * which are unreferenced. All of the objects are expected to have
1295 * non-NULL fini functions.
1296 */
1297static void
1298objlist_call_fini(Objlist *list)
1299{
1300 Objlist_Entry *elm;
1301 char *saved_msg;
1302
1303 /*
1304 * Preserve the current error message since a fini function might
1305 * call into the dynamic linker and overwrite it.
1306 */
1307 saved_msg = errmsg_save();
1308 STAILQ_FOREACH(elm, list, link) {
1309 if (elm->obj->refcount == 0) {
1310 dbg("calling fini function for %s", elm->obj->path);
1311 (*elm->obj->fini)();
1312 }
1313 }
1314 errmsg_restore(saved_msg);
1315}
1316
1317/*
1318 * Call the initialization functions for each of the objects in
1319 * "list". All of the objects are expected to have non-NULL init
1320 * functions.
1321 */
1322static void
1323objlist_call_init(Objlist *list)
1324{
1325 Objlist_Entry *elm;
1326 char *saved_msg;
1327
1328 /*
1329 * Preserve the current error message since an init function might
1330 * call into the dynamic linker and overwrite it.
1331 */
1332 saved_msg = errmsg_save();
1333 STAILQ_FOREACH(elm, list, link) {
1334 dbg("calling init function for %s", elm->obj->path);
1335 (*elm->obj->init)();
1336 }
1337 errmsg_restore(saved_msg);
1338}
1339
1340static void
1341objlist_clear(Objlist *list)
1342{
1343 Objlist_Entry *elm;
1344
1345 while (!STAILQ_EMPTY(list)) {
1346 elm = STAILQ_FIRST(list);
1347 STAILQ_REMOVE_HEAD(list, link);
1348 free(elm);
1349 }
1350}
1351
1352static Objlist_Entry *
1353objlist_find(Objlist *list, const Obj_Entry *obj)
1354{
1355 Objlist_Entry *elm;
1356
1357 STAILQ_FOREACH(elm, list, link)
1358 if (elm->obj == obj)
1359 return elm;
1360 return NULL;
1361}
1362
1363static void
1364objlist_init(Objlist *list)
1365{
1366 STAILQ_INIT(list);
1367}
1368
1369static void
1370objlist_push_head(Objlist *list, Obj_Entry *obj)
1371{
1372 Objlist_Entry *elm;
1373
1374 elm = NEW(Objlist_Entry);
1375 elm->obj = obj;
1376 STAILQ_INSERT_HEAD(list, elm, link);
1377}
1378
1379static void
1380objlist_push_tail(Objlist *list, Obj_Entry *obj)
1381{
1382 Objlist_Entry *elm;
1383
1384 elm = NEW(Objlist_Entry);
1385 elm->obj = obj;
1386 STAILQ_INSERT_TAIL(list, elm, link);
1387}
1388
1389static void
1390objlist_remove(Objlist *list, Obj_Entry *obj)
1391{
1392 Objlist_Entry *elm;
1393
1394 if ((elm = objlist_find(list, obj)) != NULL) {
1395 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1396 free(elm);
1397 }
1398}
1399
1400/*
1401 * Remove all of the unreferenced objects from "list".
1402 */
1403static void
1404objlist_remove_unref(Objlist *list)
1405{
1406 Objlist newlist;
1407 Objlist_Entry *elm;
1408
1409 STAILQ_INIT(&newlist);
1410 while (!STAILQ_EMPTY(list)) {
1411 elm = STAILQ_FIRST(list);
1412 STAILQ_REMOVE_HEAD(list, link);
1413 if (elm->obj->refcount == 0)
1414 free(elm);
1415 else
1416 STAILQ_INSERT_TAIL(&newlist, elm, link);
1417 }
1418 *list = newlist;
1419}
1420
1421/*
1422 * Relocate newly-loaded shared objects. The argument is a pointer to
1423 * the Obj_Entry for the first such object. All objects from the first
1424 * to the end of the list of objects are relocated. Returns 0 on success,
1425 * or -1 on failure.
1426 */
1427static int
1428relocate_objects(Obj_Entry *first, bool bind_now)
1429{
1430 Obj_Entry *obj;
1431
1432 for (obj = first; obj != NULL; obj = obj->next) {
1433 if (obj != &obj_rtld)
1434 dbg("relocating \"%s\"", obj->path);
1435 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1436 obj->symtab == NULL || obj->strtab == NULL) {
1437 _rtld_error("%s: Shared object has no run-time symbol table",
1438 obj->path);
1439 return -1;
1440 }
1441
1442 if (obj->textrel) {
1443 /* There are relocations to the write-protected text segment. */
1444 if (mprotect(obj->mapbase, obj->textsize,
1445 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1446 _rtld_error("%s: Cannot write-enable text segment: %s",
1447 obj->path, strerror(errno));
1448 return -1;
1449 }
1450 }
1451
1452 /* Process the non-PLT relocations. */
1453 if (reloc_non_plt(obj, &obj_rtld))
1454 return -1;
1455
4b89341e
MD
1456 /*
1457 * Reprotect the text segment. Make sure it is included in the
1458 * core dump since we modified it. This unfortunately causes the
1459 * entire text segment to core-out but we don't have much of a
1460 * choice. We could try to only reenable core dumps on pages
1461 * in which relocations occured but that is likely most of the text
1462 * pages anyway, and even that would not work because the rest of
1463 * the text pages would wind up as a read-only OBJT_DEFAULT object
1464 * (created due to our modifications) backed by the original OBJT_VNODE
1465 * object, and the ELF coredump code is currently only able to dump
1466 * vnode records for pure vnode-backed mappings, not vnode backings
1467 * to memory objects.
1468 */
1469 if (obj->textrel) {
1470 madvise(obj->mapbase, obj->textsize, MADV_CORE);
984263bc
MD
1471 if (mprotect(obj->mapbase, obj->textsize,
1472 PROT_READ|PROT_EXEC) == -1) {
1473 _rtld_error("%s: Cannot write-protect text segment: %s",
1474 obj->path, strerror(errno));
1475 return -1;
1476 }
1477 }
1478
1479 /* Process the PLT relocations. */
1480 if (reloc_plt(obj) == -1)
1481 return -1;
1482 /* Relocate the jump slots if we are doing immediate binding. */
1483 if (bind_now)
1484 if (reloc_jmpslots(obj) == -1)
1485 return -1;
1486
1487
1488 /*
1489 * Set up the magic number and version in the Obj_Entry. These
1490 * were checked in the crt1.o from the original ElfKit, so we
1491 * set them for backward compatibility.
1492 */
1493 obj->magic = RTLD_MAGIC;
1494 obj->version = RTLD_VERSION;
1495
1496 /* Set the special PLT or GOT entries. */
1497 init_pltgot(obj);
1498 }
1499
1500 return 0;
1501}
1502
1503/*
1504 * Cleanup procedure. It will be called (by the atexit mechanism) just
1505 * before the process exits.
1506 */
1507static void
1508rtld_exit(void)
1509{
1510 Obj_Entry *obj;
1511
1512 dbg("rtld_exit()");
1513 /* Clear all the reference counts so the fini functions will be called. */
1514 for (obj = obj_list; obj != NULL; obj = obj->next)
1515 obj->refcount = 0;
1516 objlist_call_fini(&list_fini);
1517 /* No need to remove the items from the list, since we are exiting. */
1518}
1519
1520static void *
1521path_enumerate(const char *path, path_enum_proc callback, void *arg)
1522{
1523 if (path == NULL)
1524 return (NULL);
1525
1526 path += strspn(path, ":;");
1527 while (*path != '\0') {
1528 size_t len;
1529 char *res;
1530
1531 len = strcspn(path, ":;");
1532 res = callback(path, len, arg);
1533
1534 if (res != NULL)
1535 return (res);
1536
1537 path += len;
1538 path += strspn(path, ":;");
1539 }
1540
1541 return (NULL);
1542}
1543
1544struct try_library_args {
1545 const char *name;
1546 size_t namelen;
1547 char *buffer;
1548 size_t buflen;
1549};
1550
1551static void *
1552try_library_path(const char *dir, size_t dirlen, void *param)
1553{
1554 struct try_library_args *arg;
1555
1556 arg = param;
1557 if (*dir == '/' || trust) {
1558 char *pathname;
1559
1560 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1561 return (NULL);
1562
1563 pathname = arg->buffer;
1564 strncpy(pathname, dir, dirlen);
1565 pathname[dirlen] = '/';
1566 strcpy(pathname + dirlen + 1, arg->name);
1567
1568 dbg(" Trying \"%s\"", pathname);
1569 if (access(pathname, F_OK) == 0) { /* We found it */
1570 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1571 strcpy(pathname, arg->buffer);
1572 return (pathname);
1573 }
1574 }
1575 return (NULL);
1576}
1577
1578static char *
1579search_library_path(const char *name, const char *path)
1580{
1581 char *p;
1582 struct try_library_args arg;
1583
1584 if (path == NULL)
1585 return NULL;
1586
1587 arg.name = name;
1588 arg.namelen = strlen(name);
1589 arg.buffer = xmalloc(PATH_MAX);
1590 arg.buflen = PATH_MAX;
1591
1592 p = path_enumerate(path, try_library_path, &arg);
1593
1594 free(arg.buffer);
1595
1596 return (p);
1597}
1598
1599int
1600dlclose(void *handle)
1601{
1602 Obj_Entry *root;
1603
1604 wlock_acquire();
1605 root = dlcheck(handle);
1606 if (root == NULL) {
1607 wlock_release();
1608 return -1;
1609 }
1610
1611 /* Unreference the object and its dependencies. */
1612 root->dl_refcount--;
1613 unref_dag(root);
1614
1615 if (root->refcount == 0) {
1616 /*
1617 * The object is no longer referenced, so we must unload it.
1618 * First, call the fini functions with no locks held.
1619 */
1620 wlock_release();
1621 objlist_call_fini(&list_fini);
1622 wlock_acquire();
1623 objlist_remove_unref(&list_fini);
1624
1625 /* Finish cleaning up the newly-unreferenced objects. */
1626 GDB_STATE(RT_DELETE,&root->linkmap);
1627 unload_object(root);
1628 GDB_STATE(RT_CONSISTENT,NULL);
1629 }
1630 wlock_release();
1631 return 0;
1632}
1633
1634const char *
1635dlerror(void)
1636{
1637 char *msg = error_message;
1638 error_message = NULL;
1639 return msg;
1640}
1641
1642/*
1643 * This function is deprecated and has no effect.
1644 */
1645void
1646dllockinit(void *context,
1647 void *(*lock_create)(void *context),
1648 void (*rlock_acquire)(void *lock),
1649 void (*wlock_acquire)(void *lock),
1650 void (*lock_release)(void *lock),
1651 void (*lock_destroy)(void *lock),
1652 void (*context_destroy)(void *context))
1653{
1654 static void *cur_context;
1655 static void (*cur_context_destroy)(void *);
1656
1657 /* Just destroy the context from the previous call, if necessary. */
1658 if (cur_context_destroy != NULL)
1659 cur_context_destroy(cur_context);
1660 cur_context = context;
1661 cur_context_destroy = context_destroy;
1662}
1663
1664void *
1665dlopen(const char *name, int mode)
1666{
1667 Obj_Entry **old_obj_tail;
1668 Obj_Entry *obj;
1669 Objlist initlist;
1670 int result;
1671
1672 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1673 if (ld_tracing != NULL)
1674 environ = (char **)*get_program_var_addr("environ");
1675
1676 objlist_init(&initlist);
1677
1678 wlock_acquire();
1679 GDB_STATE(RT_ADD,NULL);
1680
1681 old_obj_tail = obj_tail;
1682 obj = NULL;
1683 if (name == NULL) {
1684 obj = obj_main;
1685 obj->refcount++;
1686 } else {
1687 char *path = find_library(name, obj_main);
1688 if (path != NULL)
1689 obj = load_object(path);
1690 }
1691
1692 if (obj) {
1693 obj->dl_refcount++;
8ca15ec8 1694 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
984263bc
MD
1695 objlist_push_tail(&list_global, obj);
1696 mode &= RTLD_MODEMASK;
1697 if (*old_obj_tail != NULL) { /* We loaded something new. */
1698 assert(*old_obj_tail == obj);
1699
1700 result = load_needed_objects(obj);
1701 if (result != -1 && ld_tracing)
1702 goto trace;
1703
1704 if (result == -1 ||
1705 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1706 obj->dl_refcount--;
1707 unref_dag(obj);
1708 if (obj->refcount == 0)
1709 unload_object(obj);
1710 obj = NULL;
1711 } else {
1712 /* Make list of init functions to call. */
1713 initlist_add_objects(obj, &obj->next, &initlist);
1714 }
1715 } else if (ld_tracing)
1716 goto trace;
1717 }
1718
1719 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1720
1721 /* Call the init functions with no locks held. */
1722 wlock_release();
1723 objlist_call_init(&initlist);
1724 wlock_acquire();
1725 objlist_clear(&initlist);
1726 wlock_release();
1727 return obj;
1728trace:
1729 trace_loaded_objects(obj);
1730 wlock_release();
1731 exit(0);
1732}
1733
1734void *
1735dlsym(void *handle, const char *name)
1736{
1737 const Obj_Entry *obj;
1738 unsigned long hash;
1739 const Elf_Sym *def;
1740 const Obj_Entry *defobj;
1741
1742 hash = elf_hash(name);
1743 def = NULL;
1744 defobj = NULL;
1745
1746 rlock_acquire();
1747 if (handle == NULL || handle == RTLD_NEXT ||
1748 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1749 void *retaddr;
1750
1751 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1752 if ((obj = obj_from_addr(retaddr)) == NULL) {
1753 _rtld_error("Cannot determine caller's shared object");
1754 rlock_release();
1755 return NULL;
1756 }
1757 if (handle == NULL) { /* Just the caller's shared object. */
1758 def = symlook_obj(name, hash, obj, true);
1759 defobj = obj;
1760 } else if (handle == RTLD_NEXT || /* Objects after caller's */
1761 handle == RTLD_SELF) { /* ... caller included */
1762 if (handle == RTLD_NEXT)
1763 obj = obj->next;
1764 for (; obj != NULL; obj = obj->next) {
1765 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1766 defobj = obj;
1767 break;
1768 }
1769 }
1770 } else {
1771 assert(handle == RTLD_DEFAULT);
1772 def = symlook_default(name, hash, obj, &defobj, true);
1773 }
1774 } else {
1775 if ((obj = dlcheck(handle)) == NULL) {
1776 rlock_release();
1777 return NULL;
1778 }
1779
1780 if (obj->mainprog) {
1781 DoneList donelist;
1782
1783 /* Search main program and all libraries loaded by it. */
1784 donelist_init(&donelist);
1785 def = symlook_list(name, hash, &list_main, &defobj, true,
1786 &donelist);
1787 } else {
1788 /*
1789 * XXX - This isn't correct. The search should include the whole
1790 * DAG rooted at the given object.
1791 */
1792 def = symlook_obj(name, hash, obj, true);
1793 defobj = obj;
1794 }
1795 }
1796
1797 if (def != NULL) {
1798 rlock_release();
1799 return defobj->relocbase + def->st_value;
1800 }
1801
1802 _rtld_error("Undefined symbol \"%s\"", name);
1803 rlock_release();
1804 return NULL;
1805}
1806
1807int
1808dladdr(const void *addr, Dl_info *info)
1809{
1810 const Obj_Entry *obj;
1811 const Elf_Sym *def;
1812 void *symbol_addr;
1813 unsigned long symoffset;
1814
1815 rlock_acquire();
1816 obj = obj_from_addr(addr);
1817 if (obj == NULL) {
1818 _rtld_error("No shared object contains address");
1819 rlock_release();
1820 return 0;
1821 }
1822 info->dli_fname = obj->path;
1823 info->dli_fbase = obj->mapbase;
1824 info->dli_saddr = (void *)0;
1825 info->dli_sname = NULL;
1826
1827 /*
1828 * Walk the symbol list looking for the symbol whose address is
1829 * closest to the address sent in.
1830 */
1831 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1832 def = obj->symtab + symoffset;
1833
1834 /*
1835 * For skip the symbol if st_shndx is either SHN_UNDEF or
1836 * SHN_COMMON.
1837 */
1838 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1839 continue;
1840
1841 /*
1842 * If the symbol is greater than the specified address, or if it
1843 * is further away from addr than the current nearest symbol,
1844 * then reject it.
1845 */
1846 symbol_addr = obj->relocbase + def->st_value;
1847 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1848 continue;
1849
1850 /* Update our idea of the nearest symbol. */
1851 info->dli_sname = obj->strtab + def->st_name;
1852 info->dli_saddr = symbol_addr;
1853
1854 /* Exact match? */
1855 if (info->dli_saddr == addr)
1856 break;
1857 }
1858 rlock_release();
1859 return 1;
1860}
1861
1862int
1863dlinfo(void *handle, int request, void *p)
1864{
1865 const Obj_Entry *obj;
1866 int error;
1867
1868 rlock_acquire();
1869
1870 if (handle == NULL || handle == RTLD_SELF) {
1871 void *retaddr;
1872
1873 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1874 if ((obj = obj_from_addr(retaddr)) == NULL)
1875 _rtld_error("Cannot determine caller's shared object");
1876 } else
1877 obj = dlcheck(handle);
1878
1879 if (obj == NULL) {
1880 rlock_release();
1881 return (-1);
1882 }
1883
1884 error = 0;
1885 switch (request) {
1886 case RTLD_DI_LINKMAP:
1887 *((struct link_map const **)p) = &obj->linkmap;
1888 break;
1889 case RTLD_DI_ORIGIN:
1890 error = rtld_dirname(obj->path, p);
1891 break;
1892
1893 case RTLD_DI_SERINFOSIZE:
1894 case RTLD_DI_SERINFO:
1895 error = do_search_info(obj, request, (struct dl_serinfo *)p);
1896 break;
1897
1898 default:
1899 _rtld_error("Invalid request %d passed to dlinfo()", request);
1900 error = -1;
1901 }
1902
1903 rlock_release();
1904
1905 return (error);
1906}
1907
1908struct fill_search_info_args {
1909 int request;
1910 unsigned int flags;
1911 Dl_serinfo *serinfo;
1912 Dl_serpath *serpath;
1913 char *strspace;
1914};
1915
1916static void *
1917fill_search_info(const char *dir, size_t dirlen, void *param)
1918{
1919 struct fill_search_info_args *arg;
1920
1921 arg = param;
1922
1923 if (arg->request == RTLD_DI_SERINFOSIZE) {
1924 arg->serinfo->dls_cnt ++;
1925 arg->serinfo->dls_size += dirlen + 1;
1926 } else {
1927 struct dl_serpath *s_entry;
1928
1929 s_entry = arg->serpath;
1930 s_entry->dls_name = arg->strspace;
1931 s_entry->dls_flags = arg->flags;
1932
1933 strncpy(arg->strspace, dir, dirlen);
1934 arg->strspace[dirlen] = '\0';
1935
1936 arg->strspace += dirlen + 1;
1937 arg->serpath++;
1938 }
1939
1940 return (NULL);
1941}
1942
1943static int
1944do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
1945{
1946 struct dl_serinfo _info;
1947 struct fill_search_info_args args;
1948
1949 args.request = RTLD_DI_SERINFOSIZE;
1950 args.serinfo = &_info;
1951
1952 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1953 _info.dls_cnt = 0;
1954
1955 path_enumerate(ld_library_path, fill_search_info, &args);
1956 path_enumerate(obj->rpath, fill_search_info, &args);
1957 path_enumerate(gethints(), fill_search_info, &args);
1958 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
1959
1960
1961 if (request == RTLD_DI_SERINFOSIZE) {
1962 info->dls_size = _info.dls_size;
1963 info->dls_cnt = _info.dls_cnt;
1964 return (0);
1965 }
1966
1967 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
1968 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
1969 return (-1);
1970 }
1971
1972 args.request = RTLD_DI_SERINFO;
1973 args.serinfo = info;
1974 args.serpath = &info->dls_serpath[0];
1975 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
1976
1977 args.flags = LA_SER_LIBPATH;
1978 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
1979 return (-1);
1980
1981 args.flags = LA_SER_RUNPATH;
1982 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
1983 return (-1);
1984
1985 args.flags = LA_SER_CONFIG;
1986 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
1987 return (-1);
1988
1989 args.flags = LA_SER_DEFAULT;
1990 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
1991 return (-1);
1992 return (0);
1993}
1994
1995static int
1996rtld_dirname(const char *path, char *bname)
1997{
1998 const char *endp;
1999
2000 /* Empty or NULL string gets treated as "." */
2001 if (path == NULL || *path == '\0') {
2002 bname[0] = '.';
2003 bname[1] = '\0';
2004 return (0);
2005 }
2006
2007 /* Strip trailing slashes */
2008 endp = path + strlen(path) - 1;
2009 while (endp > path && *endp == '/')
2010 endp--;
2011
2012 /* Find the start of the dir */
2013 while (endp > path && *endp != '/')
2014 endp--;
2015
2016 /* Either the dir is "/" or there are no slashes */
2017 if (endp == path) {
2018 bname[0] = *endp == '/' ? '/' : '.';
2019 bname[1] = '\0';
2020 return (0);
2021 } else {
2022 do {
2023 endp--;
2024 } while (endp > path && *endp == '/');
2025 }
2026
2027 if (endp - path + 2 > PATH_MAX)
2028 {
2029 _rtld_error("Filename is too long: %s", path);
2030 return(-1);
2031 }
2032
2033 strncpy(bname, path, endp - path + 1);
2034 bname[endp - path + 1] = '\0';
2035 return (0);
2036}
2037
2038static void
2039linkmap_add(Obj_Entry *obj)
2040{
2041 struct link_map *l = &obj->linkmap;
2042 struct link_map *prev;
2043
2044 obj->linkmap.l_name = obj->path;
2045 obj->linkmap.l_addr = obj->mapbase;
2046 obj->linkmap.l_ld = obj->dynamic;
2047#ifdef __mips__
2048 /* GDB needs load offset on MIPS to use the symbols */
2049 obj->linkmap.l_offs = obj->relocbase;
2050#endif
2051
2052 if (r_debug.r_map == NULL) {
2053 r_debug.r_map = l;
2054 return;
2055 }
2056
2057 /*
2058 * Scan to the end of the list, but not past the entry for the
2059 * dynamic linker, which we want to keep at the very end.
2060 */
2061 for (prev = r_debug.r_map;
2062 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2063 prev = prev->l_next)
2064 ;
2065
2066 /* Link in the new entry. */
2067 l->l_prev = prev;
2068 l->l_next = prev->l_next;
2069 if (l->l_next != NULL)
2070 l->l_next->l_prev = l;
2071 prev->l_next = l;
2072}
2073
2074static void
2075linkmap_delete(Obj_Entry *obj)
2076{
2077 struct link_map *l = &obj->linkmap;
2078
2079 if (l->l_prev == NULL) {
2080 if ((r_debug.r_map = l->l_next) != NULL)
2081 l->l_next->l_prev = NULL;
2082 return;
2083 }
2084
2085 if ((l->l_prev->l_next = l->l_next) != NULL)
2086 l->l_next->l_prev = l->l_prev;
2087}
2088
2089/*
2090 * Function for the debugger to set a breakpoint on to gain control.
2091 *
2092 * The two parameters allow the debugger to easily find and determine
2093 * what the runtime loader is doing and to whom it is doing it.
2094 *
2095 * When the loadhook trap is hit (r_debug_state, set at program
2096 * initialization), the arguments can be found on the stack:
2097 *
2098 * +8 struct link_map *m
2099 * +4 struct r_debug *rd
2100 * +0 RetAddr
2101 */
2102void
2103r_debug_state(struct r_debug* rd, struct link_map *m)
2104{
2105}
2106
2107/*
2108 * Get address of the pointer variable in the main program.
2109 */
2110static const void **
2111get_program_var_addr(const char *name)
2112{
2113 const Obj_Entry *obj;
2114 unsigned long hash;
2115
2116 hash = elf_hash(name);
2117 for (obj = obj_main; obj != NULL; obj = obj->next) {
2118 const Elf_Sym *def;
2119
2120 if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2121 const void **addr;
2122
2123 addr = (const void **)(obj->relocbase + def->st_value);
2124 return addr;
2125 }
2126 }
2127 return NULL;
2128}
2129
2130/*
2131 * Set a pointer variable in the main program to the given value. This
2132 * is used to set key variables such as "environ" before any of the
2133 * init functions are called.
2134 */
2135static void
2136set_program_var(const char *name, const void *value)
2137{
2138 const void **addr;
2139
2140 if ((addr = get_program_var_addr(name)) != NULL) {
2141 dbg("\"%s\": *%p <-- %p", name, addr, value);
2142 *addr = value;
2143 }
2144}
2145
8ca15ec8
MD
2146/*
2147 * This is a special version of getenv which is far more efficient
2148 * at finding LD_ environment vars.
2149 */
2150static
2151const char *
2152_getenv_ld(const char *id)
2153{
2154 const char *envp;
2155 int i, j;
2156 int idlen = strlen(id);
2157
2158 if (ld_index == LD_ARY_CACHE)
2159 return(getenv(id));
2160 if (ld_index == 0) {
2161 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2162 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2163 ld_ary[j++] = envp;
2164 }
2165 if (j == 0)
2166 ld_ary[j++] = "";
2167 ld_index = j;
2168 }
2169 for (i = ld_index - 1; i >= 0; --i) {
2170 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2171 return(ld_ary[i] + idlen + 1);
2172 }
2173 return(NULL);
2174}
2175
984263bc
MD
2176/*
2177 * Given a symbol name in a referencing object, find the corresponding
2178 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2179 * no definition was found. Returns a pointer to the Obj_Entry of the
2180 * defining object via the reference parameter DEFOBJ_OUT.
2181 */
2182static const Elf_Sym *
2183symlook_default(const char *name, unsigned long hash,
2184 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2185{
2186 DoneList donelist;
2187 const Elf_Sym *def;
2188 const Elf_Sym *symp;
2189 const Obj_Entry *obj;
2190 const Obj_Entry *defobj;
2191 const Objlist_Entry *elm;
2192 def = NULL;
2193 defobj = NULL;
2194 donelist_init(&donelist);
2195
2196 /* Look first in the referencing object if linked symbolically. */
2197 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2198 symp = symlook_obj(name, hash, refobj, in_plt);
2199 if (symp != NULL) {
2200 def = symp;
2201 defobj = refobj;
2202 }
2203 }
2204
2205 /* Search all objects loaded at program start up. */
2206 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2207 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2208 if (symp != NULL &&
2209 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2210 def = symp;
2211 defobj = obj;
2212 }
2213 }
2214
2215 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2216 STAILQ_FOREACH(elm, &list_global, link) {
2217 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2218 break;
2219 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2220 &donelist);
2221 if (symp != NULL &&
2222 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2223 def = symp;
2224 defobj = obj;
2225 }
2226 }
2227
2228 /* Search all dlopened DAGs containing the referencing object. */
2229 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2230 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2231 break;
2232 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2233 &donelist);
2234 if (symp != NULL &&
2235 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2236 def = symp;
2237 defobj = obj;
2238 }
2239 }
2240
2241 /*
2242 * Search the dynamic linker itself, and possibly resolve the
2243 * symbol from there. This is how the application links to
2244 * dynamic linker services such as dlopen. Only the values listed
2245 * in the "exports" array can be resolved from the dynamic linker.
2246 */
2247 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2248 symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2249 if (symp != NULL && is_exported(symp)) {
2250 def = symp;
2251 defobj = &obj_rtld;
2252 }
2253 }
2254
2255 if (def != NULL)
2256 *defobj_out = defobj;
2257 return def;
2258}
2259
2260static const Elf_Sym *
2261symlook_list(const char *name, unsigned long hash, Objlist *objlist,
2262 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2263{
2264 const Elf_Sym *symp;
2265 const Elf_Sym *def;
2266 const Obj_Entry *defobj;
2267 const Objlist_Entry *elm;
2268
2269 def = NULL;
2270 defobj = NULL;
2271 STAILQ_FOREACH(elm, objlist, link) {
2272 if (donelist_check(dlp, elm->obj))
2273 continue;
2274 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2275 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2276 def = symp;
2277 defobj = elm->obj;
2278 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2279 break;
2280 }
2281 }
2282 }
2283 if (def != NULL)
2284 *defobj_out = defobj;
2285 return def;
2286}
2287
2288/*
2289 * Search the symbol table of a single shared object for a symbol of
2290 * the given name. Returns a pointer to the symbol, or NULL if no
2291 * definition was found.
2292 *
2293 * The symbol's hash value is passed in for efficiency reasons; that
2294 * eliminates many recomputations of the hash value.
2295 */
2296const Elf_Sym *
2297symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2298 bool in_plt)
2299{
2300 if (obj->buckets != NULL) {
2301 unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2302
2303 while (symnum != STN_UNDEF) {
2304 const Elf_Sym *symp;
2305 const char *strp;
2306
2307 if (symnum >= obj->nchains)
2308 return NULL; /* Bad object */
2309 symp = obj->symtab + symnum;
2310 strp = obj->strtab + symp->st_name;
2311
2312 if (name[0] == strp[0] && strcmp(name, strp) == 0)
2313 return symp->st_shndx != SHN_UNDEF ||
2314 (!in_plt && symp->st_value != 0 &&
2315 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2316
2317 symnum = obj->chains[symnum];
2318 }
2319 }
2320 return NULL;
2321}
2322
2323static void
2324trace_loaded_objects(Obj_Entry *obj)
2325{
8ca15ec8 2326 const char *fmt1, *fmt2, *fmt, *main_local;
984263bc
MD
2327 int c;
2328
8ca15ec8 2329 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
984263bc
MD
2330 main_local = "";
2331
8ca15ec8 2332 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
984263bc
MD
2333 fmt1 = "\t%o => %p (%x)\n";
2334
8ca15ec8 2335 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
984263bc
MD
2336 fmt2 = "\t%o (%x)\n";
2337
2338 for (; obj; obj = obj->next) {
2339 Needed_Entry *needed;
2340 char *name, *path;
2341 bool is_lib;
2342
2343 for (needed = obj->needed; needed; needed = needed->next) {
2344 if (needed->obj != NULL) {
2345 if (needed->obj->traced)
2346 continue;
2347 needed->obj->traced = true;
2348 path = needed->obj->path;
2349 } else
2350 path = "not found";
2351
2352 name = (char *)obj->strtab + needed->name;
2353 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2354
2355 fmt = is_lib ? fmt1 : fmt2;
2356 while ((c = *fmt++) != '\0') {
2357 switch (c) {
2358 default:
2359 putchar(c);
2360 continue;
2361 case '\\':
2362 switch (c = *fmt) {
2363 case '\0':
2364 continue;
2365 case 'n':
2366 putchar('\n');
2367 break;
2368 case 't':
2369 putchar('\t');
2370 break;
2371 }
2372 break;
2373 case '%':
2374 switch (c = *fmt) {
2375 case '\0':
2376 continue;
2377 case '%':
2378 default:
2379 putchar(c);
2380 break;
2381 case 'A':
2382 printf("%s", main_local);
2383 break;
2384 case 'a':
2385 printf("%s", obj_main->path);
2386 break;
2387 case 'o':
2388 printf("%s", name);
2389 break;
2390#if 0
2391 case 'm':
2392 printf("%d", sodp->sod_major);
2393 break;
2394 case 'n':
2395 printf("%d", sodp->sod_minor);
2396 break;
2397#endif
2398 case 'p':
2399 printf("%s", path);
2400 break;
2401 case 'x':
2402 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2403 break;
2404 }
2405 break;
2406 }
2407 ++fmt;
2408 }
2409 }
2410 }
2411}
2412
2413/*
2414 * Unload a dlopened object and its dependencies from memory and from
2415 * our data structures. It is assumed that the DAG rooted in the
2416 * object has already been unreferenced, and that the object has a
2417 * reference count of 0.
2418 */
2419static void
2420unload_object(Obj_Entry *root)
2421{
2422 Obj_Entry *obj;
2423 Obj_Entry **linkp;
2424
2425 assert(root->refcount == 0);
2426
2427 /*
2428 * Pass over the DAG removing unreferenced objects from
2429 * appropriate lists.
2430 */
2431 unlink_object(root);
2432
2433 /* Unmap all objects that are no longer referenced. */
2434 linkp = &obj_list->next;
2435 while ((obj = *linkp) != NULL) {
2436 if (obj->refcount == 0) {
2437 dbg("unloading \"%s\"", obj->path);
2438 munmap(obj->mapbase, obj->mapsize);
2439 linkmap_delete(obj);
2440 *linkp = obj->next;
2441 obj_count--;
2442 obj_free(obj);
2443 } else
2444 linkp = &obj->next;
2445 }
2446 obj_tail = linkp;
2447}
2448
2449static void
2450unlink_object(Obj_Entry *root)
2451{
2452 const Needed_Entry *needed;
2453 Objlist_Entry *elm;
2454
2455 if (root->refcount == 0) {
2456 /* Remove the object from the RTLD_GLOBAL list. */
2457 objlist_remove(&list_global, root);
2458
2459 /* Remove the object from all objects' DAG lists. */
2460 STAILQ_FOREACH(elm, &root->dagmembers , link)
2461 objlist_remove(&elm->obj->dldags, root);
2462 }
2463
2464 for (needed = root->needed; needed != NULL; needed = needed->next)
2465 if (needed->obj != NULL)
2466 unlink_object(needed->obj);
2467}
2468
2469static void
2470unref_dag(Obj_Entry *root)
2471{
2472 const Needed_Entry *needed;
2473
2474 if (root->refcount == 0)
2475 return;
2476 root->refcount--;
2477 if (root->refcount == 0)
2478 for (needed = root->needed; needed != NULL; needed = needed->next)
2479 if (needed->obj != NULL)
2480 unref_dag(needed->obj);
2481}