Start working on the full-duplex journaling feature, where the target can
[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 $
588c673f 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.16 2005/02/24 16:05:22 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
984263bc 58#define PATH_RTLD "/usr/libexec/ld-elf.so.1"
8ca15ec8 59#define LD_ARY_CACHE 16
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60
61/* Types. */
62typedef void (*func_ptr_type)();
63typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
64
65/*
66 * This structure provides a reentrant way to keep a list of objects and
67 * check which ones have already been processed in some way.
68 */
69typedef struct Struct_DoneList {
70 const Obj_Entry **objs; /* Array of object pointers */
71 unsigned int num_alloc; /* Allocated size of the array */
72 unsigned int num_used; /* Number of array slots used */
73} DoneList;
74
75/*
76 * Function declarations.
77 */
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78static void die(void);
79static void digest_dynamic(Obj_Entry *);
8ca15ec8 80static const char *_getenv_ld(const char *id);
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81static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
82static Obj_Entry *dlcheck(void *);
83static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
84static bool donelist_check(DoneList *, const Obj_Entry *);
85static void errmsg_restore(char *);
86static char *errmsg_save(void);
87static void *fill_search_info(const char *, size_t, void *);
88static char *find_library(const char *, const Obj_Entry *);
b6a22d96 89static Obj_Entry *find_object(const char *);
2d6b58a8 90static Obj_Entry *find_object2(const char *, int *, struct stat *);
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91static const char *gethints(void);
92static void init_dag(Obj_Entry *);
93static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *);
94static void init_rtld(caddr_t);
95static void initlist_add_neededs(Needed_Entry *needed, Objlist *list);
96static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail,
97 Objlist *list);
98static bool is_exported(const Elf_Sym *);
99static void linkmap_add(Obj_Entry *);
100static void linkmap_delete(Obj_Entry *);
101static int load_needed_objects(Obj_Entry *);
102static int load_preload_objects(void);
103static Obj_Entry *load_object(char *);
104static void lock_check(void);
105static Obj_Entry *obj_from_addr(const void *);
106static void objlist_call_fini(Objlist *);
107static void objlist_call_init(Objlist *);
108static void objlist_clear(Objlist *);
109static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
110static void objlist_init(Objlist *);
111static void objlist_push_head(Objlist *, Obj_Entry *);
112static void objlist_push_tail(Objlist *, Obj_Entry *);
113static void objlist_remove(Objlist *, Obj_Entry *);
114static void objlist_remove_unref(Objlist *);
115static void *path_enumerate(const char *, path_enum_proc, void *);
116static int relocate_objects(Obj_Entry *, bool);
117static int rtld_dirname(const char *, char *);
118static void rtld_exit(void);
119static char *search_library_path(const char *, const char *);
120static const void **get_program_var_addr(const char *name);
121static void set_program_var(const char *, const void *);
122static const Elf_Sym *symlook_default(const char *, unsigned long hash,
123 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
124static const Elf_Sym *symlook_list(const char *, unsigned long,
125 Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
126static void trace_loaded_objects(Obj_Entry *obj);
127static void unlink_object(Obj_Entry *);
128static void unload_object(Obj_Entry *);
129static void unref_dag(Obj_Entry *);
130
131void r_debug_state(struct r_debug*, struct link_map*);
132
133/*
134 * Data declarations.
135 */
136static char *error_message; /* Message for dlerror(), or NULL */
137struct r_debug r_debug; /* for GDB; */
138static bool trust; /* False for setuid and setgid programs */
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139static const char *ld_bind_now; /* Environment variable for immediate binding */
140static const char *ld_debug; /* Environment variable for debugging */
141static const char *ld_library_path; /* Environment variable for search path */
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142static char *ld_preload; /* Environment variable for libraries to
143 load first */
8ca15ec8 144static const char *ld_tracing; /* Called from ldd(1) to print libs */
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145static Obj_Entry *obj_list; /* Head of linked list of shared objects */
146static Obj_Entry **obj_tail; /* Link field of last object in list */
8ca15ec8 147static Obj_Entry **preload_tail;
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148static Obj_Entry *obj_main; /* The main program shared object */
149static Obj_Entry obj_rtld; /* The dynamic linker shared object */
150static unsigned int obj_count; /* Number of objects in obj_list */
33a8b578 151static int ld_resident; /* Non-zero if resident */
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152static const char *ld_ary[LD_ARY_CACHE];
153static int ld_index;
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154
155static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
156 STAILQ_HEAD_INITIALIZER(list_global);
157static Objlist list_main = /* Objects loaded at program startup */
158 STAILQ_HEAD_INITIALIZER(list_main);
159static Objlist list_fini = /* Objects needing fini() calls */
160 STAILQ_HEAD_INITIALIZER(list_fini);
161
162static LockInfo lockinfo;
163
164static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
165
166#define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
167
168extern Elf_Dyn _DYNAMIC;
169#pragma weak _DYNAMIC
170
171/*
172 * These are the functions the dynamic linker exports to application
173 * programs. They are the only symbols the dynamic linker is willing
174 * to export from itself.
175 */
176static func_ptr_type exports[] = {
177 (func_ptr_type) &_rtld_error,
178 (func_ptr_type) &dlclose,
179 (func_ptr_type) &dlerror,
180 (func_ptr_type) &dlopen,
181 (func_ptr_type) &dlsym,
182 (func_ptr_type) &dladdr,
183 (func_ptr_type) &dllockinit,
184 (func_ptr_type) &dlinfo,
185 NULL
186};
187
188/*
189 * Global declarations normally provided by crt1. The dynamic linker is
190 * not built with crt1, so we have to provide them ourselves.
191 */
192char *__progname;
193char **environ;
194
195/*
196 * Fill in a DoneList with an allocation large enough to hold all of
197 * the currently-loaded objects. Keep this as a macro since it calls
198 * alloca and we want that to occur within the scope of the caller.
199 */
200#define donelist_init(dlp) \
201 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
202 assert((dlp)->objs != NULL), \
203 (dlp)->num_alloc = obj_count, \
204 (dlp)->num_used = 0)
205
206static __inline void
207rlock_acquire(void)
208{
209 lockinfo.rlock_acquire(lockinfo.thelock);
210 atomic_incr_int(&lockinfo.rcount);
211 lock_check();
212}
213
214static __inline void
215wlock_acquire(void)
216{
217 lockinfo.wlock_acquire(lockinfo.thelock);
218 atomic_incr_int(&lockinfo.wcount);
219 lock_check();
220}
221
222static __inline void
223rlock_release(void)
224{
225 atomic_decr_int(&lockinfo.rcount);
226 lockinfo.rlock_release(lockinfo.thelock);
227}
228
229static __inline void
230wlock_release(void)
231{
232 atomic_decr_int(&lockinfo.wcount);
233 lockinfo.wlock_release(lockinfo.thelock);
234}
235
236/*
237 * Main entry point for dynamic linking. The first argument is the
238 * stack pointer. The stack is expected to be laid out as described
239 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
240 * Specifically, the stack pointer points to a word containing
241 * ARGC. Following that in the stack is a null-terminated sequence
242 * of pointers to argument strings. Then comes a null-terminated
243 * sequence of pointers to environment strings. Finally, there is a
244 * sequence of "auxiliary vector" entries.
245 *
246 * The second argument points to a place to store the dynamic linker's
247 * exit procedure pointer and the third to a place to store the main
248 * program's object.
249 *
250 * The return value is the main program's entry point.
251 */
252func_ptr_type
253_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
254{
255 Elf_Auxinfo *aux_info[AT_COUNT];
256 int i;
257 int argc;
258 char **argv;
259 char **env;
260 Elf_Auxinfo *aux;
261 Elf_Auxinfo *auxp;
262 const char *argv0;
263 Obj_Entry *obj;
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264 Objlist initlist;
265
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266 ld_index = 0; /* don't use old env cache in case we are resident */
267
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268 /*
269 * On entry, the dynamic linker itself has not been relocated yet.
270 * Be very careful not to reference any global data until after
271 * init_rtld has returned. It is OK to reference file-scope statics
272 * and string constants, and to call static and global functions.
273 */
274
275 /* Find the auxiliary vector on the stack. */
276 argc = *sp++;
277 argv = (char **) sp;
278 sp += argc + 1; /* Skip over arguments and NULL terminator */
279 env = (char **) sp;
984263bc 280
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281 /*
282 * If we aren't already resident we have to dig out some more info.
283 * Note that auxinfo does not exist when we are resident.
284 */
285 if (ld_resident == 0) {
286 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
287 ;
288 aux = (Elf_Auxinfo *) sp;
289
290 /* Digest the auxiliary vector. */
291 for (i = 0; i < AT_COUNT; i++)
292 aux_info[i] = NULL;
293 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
294 if (auxp->a_type < AT_COUNT)
295 aux_info[auxp->a_type] = auxp;
296 }
297
298 /* Initialize and relocate ourselves. */
299 assert(aux_info[AT_BASE] != NULL);
300 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
301 }
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302
303 __progname = obj_rtld.path;
304 argv0 = argv[0] != NULL ? argv[0] : "(null)";
305 environ = env;
306
8ca15ec8 307 trust = (geteuid() == getuid()) && (getegid() == getgid());
984263bc 308
8ca15ec8 309 ld_bind_now = _getenv_ld("LD_BIND_NOW");
984263bc 310 if (trust) {
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311 ld_debug = _getenv_ld("LD_DEBUG");
312 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
313 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
984263bc 314 }
8ca15ec8 315 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
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316
317 if (ld_debug != NULL && *ld_debug != '\0')
318 debug = 1;
319 dbg("%s is initialized, base address = %p", __progname,
320 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
321 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
322 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
323
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324 /*
325 * If we are resident we can skip work that we have already done.
326 * Note that the stack is reset and there is no Elf_Auxinfo
327 * when running from a resident image, and the static globals setup
328 * between here and resident_skip will have already been setup.
329 */
8ca15ec8 330 if (ld_resident)
33a8b578 331 goto resident_skip1;
33a8b578 332
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333 /*
334 * Load the main program, or process its program header if it is
335 * already loaded.
336 */
337 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
338 int fd = aux_info[AT_EXECFD]->a_un.a_val;
339 dbg("loading main program");
340 obj_main = map_object(fd, argv0, NULL);
341 close(fd);
342 if (obj_main == NULL)
343 die();
344 } else { /* Main program already loaded. */
345 const Elf_Phdr *phdr;
346 int phnum;
347 caddr_t entry;
348
349 dbg("processing main program's program header");
350 assert(aux_info[AT_PHDR] != NULL);
351 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
352 assert(aux_info[AT_PHNUM] != NULL);
353 phnum = aux_info[AT_PHNUM]->a_un.a_val;
354 assert(aux_info[AT_PHENT] != NULL);
355 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
356 assert(aux_info[AT_ENTRY] != NULL);
357 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
358 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
359 die();
360 }
361
362 obj_main->path = xstrdup(argv0);
363 obj_main->mainprog = true;
364
365 /*
366 * Get the actual dynamic linker pathname from the executable if
367 * possible. (It should always be possible.) That ensures that
368 * gdb will find the right dynamic linker even if a non-standard
369 * one is being used.
370 */
371 if (obj_main->interp != NULL &&
372 strcmp(obj_main->interp, obj_rtld.path) != 0) {
373 free(obj_rtld.path);
374 obj_rtld.path = xstrdup(obj_main->interp);
b7b05c9f 375 __progname = obj_rtld.path;
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376 }
377
378 digest_dynamic(obj_main);
379
380 linkmap_add(obj_main);
381 linkmap_add(&obj_rtld);
382
383 /* Link the main program into the list of objects. */
384 *obj_tail = obj_main;
385 obj_tail = &obj_main->next;
386 obj_count++;
387 obj_main->refcount++;
388 /* Make sure we don't call the main program's init and fini functions. */
389 obj_main->init = obj_main->fini = NULL;
390
391 /* Initialize a fake symbol for resolving undefined weak references. */
392 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
393 sym_zero.st_shndx = SHN_ABS;
394
395 dbg("loading LD_PRELOAD libraries");
396 if (load_preload_objects() == -1)
397 die();
398 preload_tail = obj_tail;
399
400 dbg("loading needed objects");
401 if (load_needed_objects(obj_main) == -1)
402 die();
403
404 /* Make a list of all objects loaded at startup. */
405 for (obj = obj_list; obj != NULL; obj = obj->next)
406 objlist_push_tail(&list_main, obj);
407
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408resident_skip1:
409
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410 if (ld_tracing) { /* We're done */
411 trace_loaded_objects(obj_main);
412 exit(0);
413 }
414
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415 if (ld_resident) /* XXX clean this up! */
416 goto resident_skip2;
417
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418 if (getenv("LD_DUMP_REL_PRE") != NULL) {
419 dump_relocations(obj_main);
420 exit (0);
421 }
422
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423 if (relocate_objects(obj_main,
424 ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
425 die();
984263bc 426
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427 dbg("doing copy relocations");
428 if (do_copy_relocations(obj_main) == -1)
429 die();
1c76efe5 430
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431resident_skip2:
432
8ca15ec8 433 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
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434 if (exec_sys_unregister(-1) < 0) {
435 dbg("exec_sys_unregister failed %d\n", errno);
436 exit(errno);
437 }
438 dbg("exec_sys_unregister success\n");
439 exit(0);
440 }
984263bc 441
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442 if (getenv("LD_DUMP_REL_POST") != NULL) {
443 dump_relocations(obj_main);
444 exit (0);
445 }
446
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447 dbg("initializing key program variables");
448 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
449 set_program_var("environ", env);
450
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451 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
452 extern void resident_start(void);
453 ld_resident = 1;
454 if (exec_sys_register(resident_start) < 0) {
455 dbg("exec_sys_register failed %d\n", errno);
456 exit(errno);
457 }
458 dbg("exec_sys_register success\n");
459 exit(0);
460 }
461
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462 dbg("initializing thread locks");
463 lockdflt_init(&lockinfo);
464 lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
465
466 /* Make a list of init functions to call. */
467 objlist_init(&initlist);
468 initlist_add_objects(obj_list, preload_tail, &initlist);
469
470 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
471
472 objlist_call_init(&initlist);
473 wlock_acquire();
474 objlist_clear(&initlist);
475 wlock_release();
476
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477
478
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479 dbg("transferring control to program entry point = %p", obj_main->entry);
480
481 /* Return the exit procedure and the program entry point. */
482 *exit_proc = rtld_exit;
483 *objp = obj_main;
484 return (func_ptr_type) obj_main->entry;
485}
486
487Elf_Addr
488_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
489{
490 const Elf_Rel *rel;
491 const Elf_Sym *def;
492 const Obj_Entry *defobj;
493 Elf_Addr *where;
494 Elf_Addr target;
495
496 rlock_acquire();
497 if (obj->pltrel)
498 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
499 else
500 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
501
502 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
503 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
504 if (def == NULL)
505 die();
506
507 target = (Elf_Addr)(defobj->relocbase + def->st_value);
508
509 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
510 defobj->strtab + def->st_name, basename(obj->path),
511 (void *)target, basename(defobj->path));
512
513 reloc_jmpslot(where, target);
514 rlock_release();
515 return target;
516}
517
518/*
519 * Error reporting function. Use it like printf. If formats the message
520 * into a buffer, and sets things up so that the next call to dlerror()
521 * will return the message.
522 */
523void
524_rtld_error(const char *fmt, ...)
525{
526 static char buf[512];
527 va_list ap;
528
529 va_start(ap, fmt);
530 vsnprintf(buf, sizeof buf, fmt, ap);
531 error_message = buf;
532 va_end(ap);
533}
534
535/*
536 * Return a dynamically-allocated copy of the current error message, if any.
537 */
538static char *
539errmsg_save(void)
540{
541 return error_message == NULL ? NULL : xstrdup(error_message);
542}
543
544/*
545 * Restore the current error message from a copy which was previously saved
546 * by errmsg_save(). The copy is freed.
547 */
548static void
549errmsg_restore(char *saved_msg)
550{
551 if (saved_msg == NULL)
552 error_message = NULL;
553 else {
554 _rtld_error("%s", saved_msg);
555 free(saved_msg);
556 }
557}
558
1c76efe5 559const char *
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560basename(const char *name)
561{
562 const char *p = strrchr(name, '/');
563 return p != NULL ? p + 1 : name;
564}
565
566static void
567die(void)
568{
569 const char *msg = dlerror();
570
571 if (msg == NULL)
572 msg = "Fatal error";
573 errx(1, "%s", msg);
574}
575
576/*
577 * Process a shared object's DYNAMIC section, and save the important
578 * information in its Obj_Entry structure.
579 */
580static void
581digest_dynamic(Obj_Entry *obj)
582{
583 const Elf_Dyn *dynp;
584 Needed_Entry **needed_tail = &obj->needed;
585 const Elf_Dyn *dyn_rpath = NULL;
586 int plttype = DT_REL;
587
588 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
589 switch (dynp->d_tag) {
590
591 case DT_REL:
592 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
593 break;
594
595 case DT_RELSZ:
596 obj->relsize = dynp->d_un.d_val;
597 break;
598
599 case DT_RELENT:
600 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
601 break;
602
603 case DT_JMPREL:
604 obj->pltrel = (const Elf_Rel *)
605 (obj->relocbase + dynp->d_un.d_ptr);
606 break;
607
608 case DT_PLTRELSZ:
609 obj->pltrelsize = dynp->d_un.d_val;
610 break;
611
612 case DT_RELA:
613 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
614 break;
615
616 case DT_RELASZ:
617 obj->relasize = dynp->d_un.d_val;
618 break;
619
620 case DT_RELAENT:
621 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
622 break;
623
624 case DT_PLTREL:
625 plttype = dynp->d_un.d_val;
626 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
627 break;
628
629 case DT_SYMTAB:
630 obj->symtab = (const Elf_Sym *)
631 (obj->relocbase + dynp->d_un.d_ptr);
632 break;
633
634 case DT_SYMENT:
635 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
636 break;
637
638 case DT_STRTAB:
639 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
640 break;
641
642 case DT_STRSZ:
643 obj->strsize = dynp->d_un.d_val;
644 break;
645
646 case DT_HASH:
647 {
648 const Elf_Addr *hashtab = (const Elf_Addr *)
649 (obj->relocbase + dynp->d_un.d_ptr);
650 obj->nbuckets = hashtab[0];
651 obj->nchains = hashtab[1];
652 obj->buckets = hashtab + 2;
653 obj->chains = obj->buckets + obj->nbuckets;
654 }
655 break;
656
657 case DT_NEEDED:
658 if (!obj->rtld) {
659 Needed_Entry *nep = NEW(Needed_Entry);
660 nep->name = dynp->d_un.d_val;
661 nep->obj = NULL;
662 nep->next = NULL;
663
664 *needed_tail = nep;
665 needed_tail = &nep->next;
666 }
667 break;
668
669 case DT_PLTGOT:
670 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
671 break;
672
673 case DT_TEXTREL:
674 obj->textrel = true;
675 break;
676
677 case DT_SYMBOLIC:
678 obj->symbolic = true;
679 break;
680
681 case DT_RPATH:
167f7029 682 case DT_RUNPATH: /* XXX: process separately */
984263bc
MD
683 /*
684 * We have to wait until later to process this, because we
685 * might not have gotten the address of the string table yet.
686 */
687 dyn_rpath = dynp;
688 break;
689
690 case DT_SONAME:
691 /* Not used by the dynamic linker. */
692 break;
693
694 case DT_INIT:
695 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
696 break;
697
698 case DT_FINI:
699 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
700 break;
701
702 case DT_DEBUG:
703 /* XXX - not implemented yet */
704 dbg("Filling in DT_DEBUG entry");
705 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
706 break;
707
167f7029
JS
708 case DT_FLAGS:
709 if (dynp->d_un.d_val & DF_ORIGIN) {
710 obj->origin_path = xmalloc(PATH_MAX);
711 if (rtld_dirname(obj->path, obj->origin_path) == -1)
712 die();
713 }
714 if (dynp->d_un.d_val & DF_SYMBOLIC)
715 obj->symbolic = true;
716 if (dynp->d_un.d_val & DF_TEXTREL)
717 obj->textrel = true;
718 if (dynp->d_un.d_val & DF_BIND_NOW)
719 obj->bind_now = true;
720 if (dynp->d_un.d_val & DF_STATIC_TLS)
721 ;
722 break;
723
984263bc
MD
724 default:
725 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
726 break;
727 }
728 }
729
730 obj->traced = false;
731
732 if (plttype == DT_RELA) {
733 obj->pltrela = (const Elf_Rela *) obj->pltrel;
734 obj->pltrel = NULL;
735 obj->pltrelasize = obj->pltrelsize;
736 obj->pltrelsize = 0;
737 }
738
739 if (dyn_rpath != NULL)
740 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
741}
742
743/*
744 * Process a shared object's program header. This is used only for the
745 * main program, when the kernel has already loaded the main program
746 * into memory before calling the dynamic linker. It creates and
747 * returns an Obj_Entry structure.
748 */
749static Obj_Entry *
750digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
751{
752 Obj_Entry *obj;
753 const Elf_Phdr *phlimit = phdr + phnum;
754 const Elf_Phdr *ph;
755 int nsegs = 0;
756
757 obj = obj_new();
758 for (ph = phdr; ph < phlimit; ph++) {
759 switch (ph->p_type) {
760
761 case PT_PHDR:
762 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
763 _rtld_error("%s: invalid PT_PHDR", path);
764 return NULL;
765 }
766 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
767 obj->phsize = ph->p_memsz;
768 break;
769
770 case PT_INTERP:
771 obj->interp = (const char *) ph->p_vaddr;
772 break;
773
774 case PT_LOAD:
775 if (nsegs == 0) { /* First load segment */
776 obj->vaddrbase = trunc_page(ph->p_vaddr);
777 obj->mapbase = (caddr_t) obj->vaddrbase;
778 obj->relocbase = obj->mapbase - obj->vaddrbase;
779 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
780 obj->vaddrbase;
781 } else { /* Last load segment */
782 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
783 obj->vaddrbase;
784 }
785 nsegs++;
786 break;
787
788 case PT_DYNAMIC:
789 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
790 break;
791 }
792 }
793 if (nsegs < 1) {
794 _rtld_error("%s: too few PT_LOAD segments", path);
795 return NULL;
796 }
797
798 obj->entry = entry;
799 return obj;
800}
801
802static Obj_Entry *
803dlcheck(void *handle)
804{
805 Obj_Entry *obj;
806
807 for (obj = obj_list; obj != NULL; obj = obj->next)
808 if (obj == (Obj_Entry *) handle)
809 break;
810
811 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
812 _rtld_error("Invalid shared object handle %p", handle);
813 return NULL;
814 }
815 return obj;
816}
817
818/*
819 * If the given object is already in the donelist, return true. Otherwise
820 * add the object to the list and return false.
821 */
822static bool
823donelist_check(DoneList *dlp, const Obj_Entry *obj)
824{
825 unsigned int i;
826
827 for (i = 0; i < dlp->num_used; i++)
828 if (dlp->objs[i] == obj)
829 return true;
830 /*
831 * Our donelist allocation should always be sufficient. But if
832 * our threads locking isn't working properly, more shared objects
833 * could have been loaded since we allocated the list. That should
834 * never happen, but we'll handle it properly just in case it does.
835 */
836 if (dlp->num_used < dlp->num_alloc)
837 dlp->objs[dlp->num_used++] = obj;
838 return false;
839}
840
841/*
842 * Hash function for symbol table lookup. Don't even think about changing
843 * this. It is specified by the System V ABI.
844 */
845unsigned long
846elf_hash(const char *name)
847{
848 const unsigned char *p = (const unsigned char *) name;
849 unsigned long h = 0;
850 unsigned long g;
851
852 while (*p != '\0') {
853 h = (h << 4) + *p++;
854 if ((g = h & 0xf0000000) != 0)
855 h ^= g >> 24;
856 h &= ~g;
857 }
858 return h;
859}
860
861/*
862 * Find the library with the given name, and return its full pathname.
863 * The returned string is dynamically allocated. Generates an error
864 * message and returns NULL if the library cannot be found.
865 *
866 * If the second argument is non-NULL, then it refers to an already-
867 * loaded shared object, whose library search path will be searched.
868 *
869 * The search order is:
984263bc 870 * LD_LIBRARY_PATH
4e390e27 871 * rpath in the referencing file
984263bc
MD
872 * ldconfig hints
873 * /usr/lib
874 */
875static char *
876find_library(const char *name, const Obj_Entry *refobj)
877{
878 char *pathname;
879
880 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
881 if (name[0] != '/' && !trust) {
882 _rtld_error("Absolute pathname required for shared object \"%s\"",
883 name);
884 return NULL;
885 }
886 return xstrdup(name);
887 }
888
889 dbg(" Searching for \"%s\"", name);
890
891 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
892 (refobj != NULL &&
893 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
894 (pathname = search_library_path(name, gethints())) != NULL ||
895 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
896 return pathname;
897
446c0d3a
JS
898 if(refobj != NULL && refobj->path != NULL) {
899 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
900 name, basename(refobj->path));
901 } else {
902 _rtld_error("Shared object \"%s\" not found", name);
903 }
984263bc
MD
904 return NULL;
905}
906
907/*
908 * Given a symbol number in a referencing object, find the corresponding
909 * definition of the symbol. Returns a pointer to the symbol, or NULL if
910 * no definition was found. Returns a pointer to the Obj_Entry of the
911 * defining object via the reference parameter DEFOBJ_OUT.
912 */
913const Elf_Sym *
914find_symdef(unsigned long symnum, const Obj_Entry *refobj,
915 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
916{
917 const Elf_Sym *ref;
918 const Elf_Sym *def;
919 const Obj_Entry *defobj;
920 const char *name;
921 unsigned long hash;
922
923 /*
924 * If we have already found this symbol, get the information from
925 * the cache.
926 */
927 if (symnum >= refobj->nchains)
928 return NULL; /* Bad object */
929 if (cache != NULL && cache[symnum].sym != NULL) {
930 *defobj_out = cache[symnum].obj;
931 return cache[symnum].sym;
932 }
933
934 ref = refobj->symtab + symnum;
935 name = refobj->strtab + ref->st_name;
936 hash = elf_hash(name);
937 defobj = NULL;
938
939 def = symlook_default(name, hash, refobj, &defobj, in_plt);
940
941 /*
942 * If we found no definition and the reference is weak, treat the
943 * symbol as having the value zero.
944 */
945 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
946 def = &sym_zero;
947 defobj = obj_main;
948 }
949
950 if (def != NULL) {
951 *defobj_out = defobj;
952 /* Record the information in the cache to avoid subsequent lookups. */
953 if (cache != NULL) {
954 cache[symnum].sym = def;
955 cache[symnum].obj = defobj;
956 }
957 } else
958 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
959 return def;
960}
961
962/*
963 * Return the search path from the ldconfig hints file, reading it if
964 * necessary. Returns NULL if there are problems with the hints file,
965 * or if the search path there is empty.
966 */
967static const char *
968gethints(void)
969{
970 static char *hints;
971
972 if (hints == NULL) {
973 int fd;
974 struct elfhints_hdr hdr;
975 char *p;
976
977 /* Keep from trying again in case the hints file is bad. */
978 hints = "";
979
980 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
981 return NULL;
982 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
983 hdr.magic != ELFHINTS_MAGIC ||
984 hdr.version != 1) {
985 close(fd);
986 return NULL;
987 }
988 p = xmalloc(hdr.dirlistlen + 1);
989 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
990 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
991 free(p);
992 close(fd);
993 return NULL;
994 }
995 hints = p;
996 close(fd);
997 }
998 return hints[0] != '\0' ? hints : NULL;
999}
1000
1001static void
1002init_dag(Obj_Entry *root)
1003{
1004 DoneList donelist;
1005
1006 donelist_init(&donelist);
1007 init_dag1(root, root, &donelist);
1008}
1009
1010static void
1011init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1012{
1013 const Needed_Entry *needed;
1014
1015 if (donelist_check(dlp, obj))
1016 return;
1017 objlist_push_tail(&obj->dldags, root);
1018 objlist_push_tail(&root->dagmembers, obj);
1019 for (needed = obj->needed; needed != NULL; needed = needed->next)
1020 if (needed->obj != NULL)
1021 init_dag1(root, needed->obj, dlp);
1022}
1023
1024/*
1025 * Initialize the dynamic linker. The argument is the address at which
1026 * the dynamic linker has been mapped into memory. The primary task of
1027 * this function is to relocate the dynamic linker.
1028 */
1029static void
1030init_rtld(caddr_t mapbase)
1031{
1032 /*
1033 * Conjure up an Obj_Entry structure for the dynamic linker.
1034 *
1035 * The "path" member is supposed to be dynamically-allocated, but we
1036 * aren't yet initialized sufficiently to do that. Below we will
1037 * replace the static version with a dynamically-allocated copy.
1038 */
1039 obj_rtld.path = PATH_RTLD;
1040 obj_rtld.rtld = true;
1041 obj_rtld.mapbase = mapbase;
1042#ifdef PIC
1043 obj_rtld.relocbase = mapbase;
1044#endif
1045 if (&_DYNAMIC != 0) {
1046 obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1047 digest_dynamic(&obj_rtld);
1048 assert(obj_rtld.needed == NULL);
1049 assert(!obj_rtld.textrel);
1050
1051 /*
1052 * Temporarily put the dynamic linker entry into the object list, so
1053 * that symbols can be found.
1054 */
1055 obj_list = &obj_rtld;
1056 obj_tail = &obj_rtld.next;
1057 obj_count = 1;
1058
1059 relocate_objects(&obj_rtld, true);
1060 }
1061
1062 /* Make the object list empty again. */
1063 obj_list = NULL;
1064 obj_tail = &obj_list;
1065 obj_count = 0;
1066
1067 /* Replace the path with a dynamically allocated copy. */
1068 obj_rtld.path = xstrdup(obj_rtld.path);
1069
1070 r_debug.r_brk = r_debug_state;
1071 r_debug.r_state = RT_CONSISTENT;
1072}
1073
1074/*
1075 * Add the init functions from a needed object list (and its recursive
1076 * needed objects) to "list". This is not used directly; it is a helper
1077 * function for initlist_add_objects(). The write lock must be held
1078 * when this function is called.
1079 */
1080static void
1081initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1082{
1083 /* Recursively process the successor needed objects. */
1084 if (needed->next != NULL)
1085 initlist_add_neededs(needed->next, list);
1086
1087 /* Process the current needed object. */
1088 if (needed->obj != NULL)
1089 initlist_add_objects(needed->obj, &needed->obj->next, list);
1090}
1091
1092/*
1093 * Scan all of the DAGs rooted in the range of objects from "obj" to
1094 * "tail" and add their init functions to "list". This recurses over
1095 * the DAGs and ensure the proper init ordering such that each object's
1096 * needed libraries are initialized before the object itself. At the
1097 * same time, this function adds the objects to the global finalization
1098 * list "list_fini" in the opposite order. The write lock must be
1099 * held when this function is called.
1100 */
1101static void
1102initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1103{
1104 if (obj->init_done)
1105 return;
1106 obj->init_done = true;
1107
1108 /* Recursively process the successor objects. */
1109 if (&obj->next != tail)
1110 initlist_add_objects(obj->next, tail, list);
1111
1112 /* Recursively process the needed objects. */
1113 if (obj->needed != NULL)
1114 initlist_add_neededs(obj->needed, list);
1115
1116 /* Add the object to the init list. */
1117 if (obj->init != NULL)
1118 objlist_push_tail(list, obj);
1119
1120 /* Add the object to the global fini list in the reverse order. */
1121 if (obj->fini != NULL)
1122 objlist_push_head(&list_fini, obj);
1123}
1124
1125static bool
1126is_exported(const Elf_Sym *def)
1127{
1128 func_ptr_type value;
1129 const func_ptr_type *p;
1130
1131 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1132 for (p = exports; *p != NULL; p++)
1133 if (*p == value)
1134 return true;
1135 return false;
1136}
1137
1138/*
1139 * Given a shared object, traverse its list of needed objects, and load
1140 * each of them. Returns 0 on success. Generates an error message and
1141 * returns -1 on failure.
1142 */
1143static int
1144load_needed_objects(Obj_Entry *first)
1145{
1146 Obj_Entry *obj;
1147
1148 for (obj = first; obj != NULL; obj = obj->next) {
1149 Needed_Entry *needed;
1150
1151 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1152 const char *name = obj->strtab + needed->name;
1153 char *path = find_library(name, obj);
1154
1155 needed->obj = NULL;
1156 if (path == NULL && !ld_tracing)
1157 return -1;
1158
1159 if (path) {
1160 needed->obj = load_object(path);
1161 if (needed->obj == NULL && !ld_tracing)
1162 return -1; /* XXX - cleanup */
1163 }
1164 }
1165 }
1166
1167 return 0;
1168}
1169
1170static int
1171load_preload_objects(void)
1172{
1173 char *p = ld_preload;
1174 static const char delim[] = " \t:;";
1175
1176 if (p == NULL)
1177 return NULL;
1178
1179 p += strspn(p, delim);
1180 while (*p != '\0') {
1181 size_t len = strcspn(p, delim);
1182 char *path;
1183 char savech;
1184
1185 savech = p[len];
1186 p[len] = '\0';
1187 if ((path = find_library(p, NULL)) == NULL)
1188 return -1;
1189 if (load_object(path) == NULL)
1190 return -1; /* XXX - cleanup */
1191 p[len] = savech;
1192 p += len;
1193 p += strspn(p, delim);
1194 }
1195 return 0;
1196}
1197
b6a22d96 1198/*
2d6b58a8 1199 * Returns a pointer to the Obj_Entry for the object with the given path.
b6a22d96
JS
1200 * Returns NULL if no matching object was found.
1201 */
1202static Obj_Entry *
1203find_object(const char *path)
1204{
1205 Obj_Entry *obj;
1206
1207 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1208 if (strcmp(obj->path, path) == 0)
1209 return(obj);
1210 }
1211 return(NULL);
1212}
1213
2d6b58a8
JS
1214/*
1215 * Returns a pointer to the Obj_Entry for the object matching device and
1216 * inode of the given path. If no matching object was found, the descriptor
1217 * is returned in fd.
1218 * Returns with obj == NULL && fd == -1 on error.
1219 */
1220static Obj_Entry *
1221find_object2(const char *path, int *fd, struct stat *sb)
1222{
1223 Obj_Entry *obj;
1224
1225 if ((*fd = open(path, O_RDONLY)) == -1) {
1226 _rtld_error("Cannot open \"%s\"", path);
1227 return(NULL);
1228 }
1229
1230 if (fstat(*fd, sb) == -1) {
1231 _rtld_error("Cannot fstat \"%s\"", path);
1232 close(*fd);
1233 *fd = -1;
1234 return NULL;
1235 }
1236
1237 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1238 if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) {
1239 close(*fd);
1240 break;
1241 }
1242 }
1243
1244 return(obj);
1245}
1246
984263bc
MD
1247/*
1248 * Load a shared object into memory, if it is not already loaded. The
1249 * argument must be a string allocated on the heap. This function assumes
1250 * responsibility for freeing it when necessary.
1251 *
1252 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1253 * on failure.
1254 */
1255static Obj_Entry *
1256load_object(char *path)
1257{
1258 Obj_Entry *obj;
1259 int fd = -1;
1260 struct stat sb;
1261
b6a22d96 1262 obj = find_object(path);
2d6b58a8 1263 if (obj != NULL) {
588c673f 1264 obj->refcount++;
2d6b58a8
JS
1265 free(path);
1266 return(obj);
1267 }
984263bc 1268
2d6b58a8 1269 obj = find_object2(path, &fd, &sb);
588c673f
JS
1270 if (obj != NULL) {
1271 obj->refcount++;
2d6b58a8
JS
1272 free(path);
1273 return(obj);
588c673f
JS
1274 } else if (fd == -1) {
1275 free(path);
1276 return(NULL);
984263bc
MD
1277 }
1278
2d6b58a8
JS
1279 dbg("loading \"%s\"", path);
1280 obj = map_object(fd, path, &sb);
1281 close(fd);
1282 if (obj == NULL) {
1283 free(path);
1284 return NULL;
1285 }
984263bc 1286
2d6b58a8
JS
1287 obj->path = path;
1288 digest_dynamic(obj);
984263bc 1289
2d6b58a8
JS
1290 *obj_tail = obj;
1291 obj_tail = &obj->next;
1292 obj_count++;
1293 linkmap_add(obj); /* for GDB & dlinfo() */
984263bc 1294
2d6b58a8
JS
1295 dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1,
1296 obj->path);
1297 if (obj->textrel)
1298 dbg(" WARNING: %s has impure text", obj->path);
984263bc
MD
1299
1300 obj->refcount++;
1301 return obj;
1302}
1303
1304/*
1305 * Check for locking violations and die if one is found.
1306 */
1307static void
1308lock_check(void)
1309{
1310 int rcount, wcount;
1311
1312 rcount = lockinfo.rcount;
1313 wcount = lockinfo.wcount;
1314 assert(rcount >= 0);
1315 assert(wcount >= 0);
1316 if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1317 _rtld_error("Application locking error: %d readers and %d writers"
1318 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1319 rcount, wcount);
1320 die();
1321 }
1322}
1323
1324static Obj_Entry *
1325obj_from_addr(const void *addr)
1326{
984263bc
MD
1327 Obj_Entry *obj;
1328
984263bc 1329 for (obj = obj_list; obj != NULL; obj = obj->next) {
984263bc
MD
1330 if (addr < (void *) obj->mapbase)
1331 continue;
c6873e56 1332 if (addr < (void *) (obj->mapbase + obj->mapsize))
984263bc
MD
1333 return obj;
1334 }
1335 return NULL;
1336}
1337
1338/*
1339 * Call the finalization functions for each of the objects in "list"
1340 * which are unreferenced. All of the objects are expected to have
1341 * non-NULL fini functions.
1342 */
1343static void
1344objlist_call_fini(Objlist *list)
1345{
1346 Objlist_Entry *elm;
1347 char *saved_msg;
1348
1349 /*
1350 * Preserve the current error message since a fini function might
1351 * call into the dynamic linker and overwrite it.
1352 */
1353 saved_msg = errmsg_save();
1354 STAILQ_FOREACH(elm, list, link) {
1355 if (elm->obj->refcount == 0) {
1356 dbg("calling fini function for %s", elm->obj->path);
1357 (*elm->obj->fini)();
1358 }
1359 }
1360 errmsg_restore(saved_msg);
1361}
1362
1363/*
1364 * Call the initialization functions for each of the objects in
1365 * "list". All of the objects are expected to have non-NULL init
1366 * functions.
1367 */
1368static void
1369objlist_call_init(Objlist *list)
1370{
1371 Objlist_Entry *elm;
1372 char *saved_msg;
1373
1374 /*
1375 * Preserve the current error message since an init function might
1376 * call into the dynamic linker and overwrite it.
1377 */
1378 saved_msg = errmsg_save();
1379 STAILQ_FOREACH(elm, list, link) {
1380 dbg("calling init function for %s", elm->obj->path);
1381 (*elm->obj->init)();
1382 }
1383 errmsg_restore(saved_msg);
1384}
1385
1386static void
1387objlist_clear(Objlist *list)
1388{
1389 Objlist_Entry *elm;
1390
1391 while (!STAILQ_EMPTY(list)) {
1392 elm = STAILQ_FIRST(list);
1393 STAILQ_REMOVE_HEAD(list, link);
1394 free(elm);
1395 }
1396}
1397
1398static Objlist_Entry *
1399objlist_find(Objlist *list, const Obj_Entry *obj)
1400{
1401 Objlist_Entry *elm;
1402
1403 STAILQ_FOREACH(elm, list, link)
1404 if (elm->obj == obj)
1405 return elm;
1406 return NULL;
1407}
1408
1409static void
1410objlist_init(Objlist *list)
1411{
1412 STAILQ_INIT(list);
1413}
1414
1415static void
1416objlist_push_head(Objlist *list, Obj_Entry *obj)
1417{
1418 Objlist_Entry *elm;
1419
1420 elm = NEW(Objlist_Entry);
1421 elm->obj = obj;
1422 STAILQ_INSERT_HEAD(list, elm, link);
1423}
1424
1425static void
1426objlist_push_tail(Objlist *list, Obj_Entry *obj)
1427{
1428 Objlist_Entry *elm;
1429
1430 elm = NEW(Objlist_Entry);
1431 elm->obj = obj;
1432 STAILQ_INSERT_TAIL(list, elm, link);
1433}
1434
1435static void
1436objlist_remove(Objlist *list, Obj_Entry *obj)
1437{
1438 Objlist_Entry *elm;
1439
1440 if ((elm = objlist_find(list, obj)) != NULL) {
1441 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1442 free(elm);
1443 }
1444}
1445
1446/*
1447 * Remove all of the unreferenced objects from "list".
1448 */
1449static void
1450objlist_remove_unref(Objlist *list)
1451{
1452 Objlist newlist;
1453 Objlist_Entry *elm;
1454
1455 STAILQ_INIT(&newlist);
1456 while (!STAILQ_EMPTY(list)) {
1457 elm = STAILQ_FIRST(list);
1458 STAILQ_REMOVE_HEAD(list, link);
1459 if (elm->obj->refcount == 0)
1460 free(elm);
1461 else
1462 STAILQ_INSERT_TAIL(&newlist, elm, link);
1463 }
1464 *list = newlist;
1465}
1466
1467/*
1468 * Relocate newly-loaded shared objects. The argument is a pointer to
1469 * the Obj_Entry for the first such object. All objects from the first
1470 * to the end of the list of objects are relocated. Returns 0 on success,
1471 * or -1 on failure.
1472 */
1473static int
1474relocate_objects(Obj_Entry *first, bool bind_now)
1475{
1476 Obj_Entry *obj;
1477
1478 for (obj = first; obj != NULL; obj = obj->next) {
1479 if (obj != &obj_rtld)
1480 dbg("relocating \"%s\"", obj->path);
1481 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1482 obj->symtab == NULL || obj->strtab == NULL) {
1483 _rtld_error("%s: Shared object has no run-time symbol table",
1484 obj->path);
1485 return -1;
1486 }
1487
1488 if (obj->textrel) {
1489 /* There are relocations to the write-protected text segment. */
1490 if (mprotect(obj->mapbase, obj->textsize,
1491 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1492 _rtld_error("%s: Cannot write-enable text segment: %s",
1493 obj->path, strerror(errno));
1494 return -1;
1495 }
1496 }
1497
1498 /* Process the non-PLT relocations. */
1499 if (reloc_non_plt(obj, &obj_rtld))
1500 return -1;
1501
4b89341e
MD
1502 /*
1503 * Reprotect the text segment. Make sure it is included in the
1504 * core dump since we modified it. This unfortunately causes the
1505 * entire text segment to core-out but we don't have much of a
1506 * choice. We could try to only reenable core dumps on pages
1507 * in which relocations occured but that is likely most of the text
1508 * pages anyway, and even that would not work because the rest of
1509 * the text pages would wind up as a read-only OBJT_DEFAULT object
1510 * (created due to our modifications) backed by the original OBJT_VNODE
1511 * object, and the ELF coredump code is currently only able to dump
1512 * vnode records for pure vnode-backed mappings, not vnode backings
1513 * to memory objects.
1514 */
1515 if (obj->textrel) {
1516 madvise(obj->mapbase, obj->textsize, MADV_CORE);
984263bc
MD
1517 if (mprotect(obj->mapbase, obj->textsize,
1518 PROT_READ|PROT_EXEC) == -1) {
1519 _rtld_error("%s: Cannot write-protect text segment: %s",
1520 obj->path, strerror(errno));
1521 return -1;
1522 }
1523 }
1524
1525 /* Process the PLT relocations. */
1526 if (reloc_plt(obj) == -1)
1527 return -1;
1528 /* Relocate the jump slots if we are doing immediate binding. */
167f7029 1529 if (obj->bind_now || bind_now)
984263bc
MD
1530 if (reloc_jmpslots(obj) == -1)
1531 return -1;
1532
1533
1534 /*
1535 * Set up the magic number and version in the Obj_Entry. These
1536 * were checked in the crt1.o from the original ElfKit, so we
1537 * set them for backward compatibility.
1538 */
1539 obj->magic = RTLD_MAGIC;
1540 obj->version = RTLD_VERSION;
1541
1542 /* Set the special PLT or GOT entries. */
1543 init_pltgot(obj);
1544 }
1545
1546 return 0;
1547}
1548
1549/*
1550 * Cleanup procedure. It will be called (by the atexit mechanism) just
1551 * before the process exits.
1552 */
1553static void
1554rtld_exit(void)
1555{
1556 Obj_Entry *obj;
1557
1558 dbg("rtld_exit()");
1559 /* Clear all the reference counts so the fini functions will be called. */
1560 for (obj = obj_list; obj != NULL; obj = obj->next)
1561 obj->refcount = 0;
1562 objlist_call_fini(&list_fini);
1563 /* No need to remove the items from the list, since we are exiting. */
1564}
1565
1566static void *
1567path_enumerate(const char *path, path_enum_proc callback, void *arg)
1568{
1569 if (path == NULL)
1570 return (NULL);
1571
1572 path += strspn(path, ":;");
1573 while (*path != '\0') {
1574 size_t len;
1575 char *res;
1576
1577 len = strcspn(path, ":;");
1578 res = callback(path, len, arg);
1579
1580 if (res != NULL)
1581 return (res);
1582
1583 path += len;
1584 path += strspn(path, ":;");
1585 }
1586
1587 return (NULL);
1588}
1589
1590struct try_library_args {
1591 const char *name;
1592 size_t namelen;
1593 char *buffer;
1594 size_t buflen;
1595};
1596
1597static void *
1598try_library_path(const char *dir, size_t dirlen, void *param)
1599{
1600 struct try_library_args *arg;
1601
1602 arg = param;
1603 if (*dir == '/' || trust) {
1604 char *pathname;
1605
1606 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1607 return (NULL);
1608
1609 pathname = arg->buffer;
1610 strncpy(pathname, dir, dirlen);
1611 pathname[dirlen] = '/';
1612 strcpy(pathname + dirlen + 1, arg->name);
1613
1614 dbg(" Trying \"%s\"", pathname);
1615 if (access(pathname, F_OK) == 0) { /* We found it */
1616 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1617 strcpy(pathname, arg->buffer);
1618 return (pathname);
1619 }
1620 }
1621 return (NULL);
1622}
1623
1624static char *
1625search_library_path(const char *name, const char *path)
1626{
1627 char *p;
1628 struct try_library_args arg;
1629
1630 if (path == NULL)
1631 return NULL;
1632
1633 arg.name = name;
1634 arg.namelen = strlen(name);
1635 arg.buffer = xmalloc(PATH_MAX);
1636 arg.buflen = PATH_MAX;
1637
1638 p = path_enumerate(path, try_library_path, &arg);
1639
1640 free(arg.buffer);
1641
1642 return (p);
1643}
1644
1645int
1646dlclose(void *handle)
1647{
1648 Obj_Entry *root;
1649
1650 wlock_acquire();
1651 root = dlcheck(handle);
1652 if (root == NULL) {
1653 wlock_release();
1654 return -1;
1655 }
1656
1657 /* Unreference the object and its dependencies. */
1658 root->dl_refcount--;
1659 unref_dag(root);
1660
1661 if (root->refcount == 0) {
1662 /*
1663 * The object is no longer referenced, so we must unload it.
1664 * First, call the fini functions with no locks held.
1665 */
1666 wlock_release();
1667 objlist_call_fini(&list_fini);
1668 wlock_acquire();
1669 objlist_remove_unref(&list_fini);
1670
1671 /* Finish cleaning up the newly-unreferenced objects. */
1672 GDB_STATE(RT_DELETE,&root->linkmap);
1673 unload_object(root);
1674 GDB_STATE(RT_CONSISTENT,NULL);
1675 }
1676 wlock_release();
1677 return 0;
1678}
1679
1680const char *
1681dlerror(void)
1682{
1683 char *msg = error_message;
1684 error_message = NULL;
1685 return msg;
1686}
1687
1688/*
1689 * This function is deprecated and has no effect.
1690 */
1691void
1692dllockinit(void *context,
1693 void *(*lock_create)(void *context),
1694 void (*rlock_acquire)(void *lock),
1695 void (*wlock_acquire)(void *lock),
1696 void (*lock_release)(void *lock),
1697 void (*lock_destroy)(void *lock),
1698 void (*context_destroy)(void *context))
1699{
1700 static void *cur_context;
1701 static void (*cur_context_destroy)(void *);
1702
1703 /* Just destroy the context from the previous call, if necessary. */
1704 if (cur_context_destroy != NULL)
1705 cur_context_destroy(cur_context);
1706 cur_context = context;
1707 cur_context_destroy = context_destroy;
1708}
1709
1710void *
1711dlopen(const char *name, int mode)
1712{
1713 Obj_Entry **old_obj_tail;
1714 Obj_Entry *obj;
1715 Objlist initlist;
1716 int result;
1717
1718 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1719 if (ld_tracing != NULL)
1720 environ = (char **)*get_program_var_addr("environ");
1721
1722 objlist_init(&initlist);
1723
1724 wlock_acquire();
1725 GDB_STATE(RT_ADD,NULL);
1726
1727 old_obj_tail = obj_tail;
1728 obj = NULL;
1729 if (name == NULL) {
1730 obj = obj_main;
1731 obj->refcount++;
1732 } else {
1733 char *path = find_library(name, obj_main);
1734 if (path != NULL)
1735 obj = load_object(path);
1736 }
1737
1738 if (obj) {
1739 obj->dl_refcount++;
8ca15ec8 1740 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
984263bc
MD
1741 objlist_push_tail(&list_global, obj);
1742 mode &= RTLD_MODEMASK;
1743 if (*old_obj_tail != NULL) { /* We loaded something new. */
1744 assert(*old_obj_tail == obj);
1745
1746 result = load_needed_objects(obj);
1747 if (result != -1 && ld_tracing)
1748 goto trace;
1749
1750 if (result == -1 ||
1751 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1752 obj->dl_refcount--;
1753 unref_dag(obj);
1754 if (obj->refcount == 0)
1755 unload_object(obj);
1756 obj = NULL;
1757 } else {
1758 /* Make list of init functions to call. */
1759 initlist_add_objects(obj, &obj->next, &initlist);
1760 }
1761 } else if (ld_tracing)
1762 goto trace;
1763 }
1764
1765 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1766
1767 /* Call the init functions with no locks held. */
1768 wlock_release();
1769 objlist_call_init(&initlist);
1770 wlock_acquire();
1771 objlist_clear(&initlist);
1772 wlock_release();
1773 return obj;
1774trace:
1775 trace_loaded_objects(obj);
1776 wlock_release();
1777 exit(0);
1778}
1779
1780void *
1781dlsym(void *handle, const char *name)
1782{
1783 const Obj_Entry *obj;
1784 unsigned long hash;
1785 const Elf_Sym *def;
1786 const Obj_Entry *defobj;
1787
1788 hash = elf_hash(name);
1789 def = NULL;
1790 defobj = NULL;
1791
1792 rlock_acquire();
1793 if (handle == NULL || handle == RTLD_NEXT ||
1794 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1795 void *retaddr;
1796
1797 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1798 if ((obj = obj_from_addr(retaddr)) == NULL) {
1799 _rtld_error("Cannot determine caller's shared object");
1800 rlock_release();
1801 return NULL;
1802 }
1803 if (handle == NULL) { /* Just the caller's shared object. */
1804 def = symlook_obj(name, hash, obj, true);
1805 defobj = obj;
1806 } else if (handle == RTLD_NEXT || /* Objects after caller's */
1807 handle == RTLD_SELF) { /* ... caller included */
1808 if (handle == RTLD_NEXT)
1809 obj = obj->next;
1810 for (; obj != NULL; obj = obj->next) {
1811 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1812 defobj = obj;
1813 break;
1814 }
1815 }
1816 } else {
1817 assert(handle == RTLD_DEFAULT);
1818 def = symlook_default(name, hash, obj, &defobj, true);
1819 }
1820 } else {
1821 if ((obj = dlcheck(handle)) == NULL) {
1822 rlock_release();
1823 return NULL;
1824 }
1825
1826 if (obj->mainprog) {
1827 DoneList donelist;
1828
1829 /* Search main program and all libraries loaded by it. */
1830 donelist_init(&donelist);
1831 def = symlook_list(name, hash, &list_main, &defobj, true,
1832 &donelist);
1833 } else {
1834 /*
1835 * XXX - This isn't correct. The search should include the whole
1836 * DAG rooted at the given object.
1837 */
1838 def = symlook_obj(name, hash, obj, true);
1839 defobj = obj;
1840 }
1841 }
1842
1843 if (def != NULL) {
1844 rlock_release();
1845 return defobj->relocbase + def->st_value;
1846 }
1847
1848 _rtld_error("Undefined symbol \"%s\"", name);
1849 rlock_release();
1850 return NULL;
1851}
1852
1853int
1854dladdr(const void *addr, Dl_info *info)
1855{
1856 const Obj_Entry *obj;
1857 const Elf_Sym *def;
1858 void *symbol_addr;
1859 unsigned long symoffset;
1860
1861 rlock_acquire();
1862 obj = obj_from_addr(addr);
1863 if (obj == NULL) {
1864 _rtld_error("No shared object contains address");
1865 rlock_release();
1866 return 0;
1867 }
1868 info->dli_fname = obj->path;
1869 info->dli_fbase = obj->mapbase;
1870 info->dli_saddr = (void *)0;
1871 info->dli_sname = NULL;
1872
1873 /*
1874 * Walk the symbol list looking for the symbol whose address is
1875 * closest to the address sent in.
1876 */
1877 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1878 def = obj->symtab + symoffset;
1879
1880 /*
1881 * For skip the symbol if st_shndx is either SHN_UNDEF or
1882 * SHN_COMMON.
1883 */
1884 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1885 continue;
1886
1887 /*
1888 * If the symbol is greater than the specified address, or if it
1889 * is further away from addr than the current nearest symbol,
1890 * then reject it.
1891 */
1892 symbol_addr = obj->relocbase + def->st_value;
1893 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1894 continue;
1895
1896 /* Update our idea of the nearest symbol. */
1897 info->dli_sname = obj->strtab + def->st_name;
1898 info->dli_saddr = symbol_addr;
1899
1900 /* Exact match? */
1901 if (info->dli_saddr == addr)
1902 break;
1903 }
1904 rlock_release();
1905 return 1;
1906}
1907
1908int
1909dlinfo(void *handle, int request, void *p)
1910{
1911 const Obj_Entry *obj;
1912 int error;
1913
1914 rlock_acquire();
1915
1916 if (handle == NULL || handle == RTLD_SELF) {
1917 void *retaddr;
1918
1919 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1920 if ((obj = obj_from_addr(retaddr)) == NULL)
1921 _rtld_error("Cannot determine caller's shared object");
1922 } else
1923 obj = dlcheck(handle);
1924
1925 if (obj == NULL) {
1926 rlock_release();
1927 return (-1);
1928 }
1929
1930 error = 0;
1931 switch (request) {
1932 case RTLD_DI_LINKMAP:
1933 *((struct link_map const **)p) = &obj->linkmap;
1934 break;
1935 case RTLD_DI_ORIGIN:
1936 error = rtld_dirname(obj->path, p);
1937 break;
1938
1939 case RTLD_DI_SERINFOSIZE:
1940 case RTLD_DI_SERINFO:
1941 error = do_search_info(obj, request, (struct dl_serinfo *)p);
1942 break;
1943
1944 default:
1945 _rtld_error("Invalid request %d passed to dlinfo()", request);
1946 error = -1;
1947 }
1948
1949 rlock_release();
1950
1951 return (error);
1952}
1953
1954struct fill_search_info_args {
1955 int request;
1956 unsigned int flags;
1957 Dl_serinfo *serinfo;
1958 Dl_serpath *serpath;
1959 char *strspace;
1960};
1961
1962static void *
1963fill_search_info(const char *dir, size_t dirlen, void *param)
1964{
1965 struct fill_search_info_args *arg;
1966
1967 arg = param;
1968
1969 if (arg->request == RTLD_DI_SERINFOSIZE) {
1970 arg->serinfo->dls_cnt ++;
1971 arg->serinfo->dls_size += dirlen + 1;
1972 } else {
1973 struct dl_serpath *s_entry;
1974
1975 s_entry = arg->serpath;
1976 s_entry->dls_name = arg->strspace;
1977 s_entry->dls_flags = arg->flags;
1978
1979 strncpy(arg->strspace, dir, dirlen);
1980 arg->strspace[dirlen] = '\0';
1981
1982 arg->strspace += dirlen + 1;
1983 arg->serpath++;
1984 }
1985
1986 return (NULL);
1987}
1988
1989static int
1990do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
1991{
1992 struct dl_serinfo _info;
1993 struct fill_search_info_args args;
1994
1995 args.request = RTLD_DI_SERINFOSIZE;
1996 args.serinfo = &_info;
1997
1998 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1999 _info.dls_cnt = 0;
2000
2001 path_enumerate(ld_library_path, fill_search_info, &args);
2002 path_enumerate(obj->rpath, fill_search_info, &args);
2003 path_enumerate(gethints(), fill_search_info, &args);
2004 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2005
2006
2007 if (request == RTLD_DI_SERINFOSIZE) {
2008 info->dls_size = _info.dls_size;
2009 info->dls_cnt = _info.dls_cnt;
2010 return (0);
2011 }
2012
2013 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2014 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2015 return (-1);
2016 }
2017
2018 args.request = RTLD_DI_SERINFO;
2019 args.serinfo = info;
2020 args.serpath = &info->dls_serpath[0];
2021 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2022
2023 args.flags = LA_SER_LIBPATH;
2024 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2025 return (-1);
2026
2027 args.flags = LA_SER_RUNPATH;
2028 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2029 return (-1);
2030
2031 args.flags = LA_SER_CONFIG;
2032 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2033 return (-1);
2034
2035 args.flags = LA_SER_DEFAULT;
2036 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2037 return (-1);
2038 return (0);
2039}
2040
2041static int
2042rtld_dirname(const char *path, char *bname)
2043{
2044 const char *endp;
2045
2046 /* Empty or NULL string gets treated as "." */
2047 if (path == NULL || *path == '\0') {
2048 bname[0] = '.';
2049 bname[1] = '\0';
2050 return (0);
2051 }
2052
2053 /* Strip trailing slashes */
2054 endp = path + strlen(path) - 1;
2055 while (endp > path && *endp == '/')
2056 endp--;
2057
2058 /* Find the start of the dir */
2059 while (endp > path && *endp != '/')
2060 endp--;
2061
2062 /* Either the dir is "/" or there are no slashes */
2063 if (endp == path) {
2064 bname[0] = *endp == '/' ? '/' : '.';
2065 bname[1] = '\0';
2066 return (0);
2067 } else {
2068 do {
2069 endp--;
2070 } while (endp > path && *endp == '/');
2071 }
2072
2073 if (endp - path + 2 > PATH_MAX)
2074 {
2075 _rtld_error("Filename is too long: %s", path);
2076 return(-1);
2077 }
2078
2079 strncpy(bname, path, endp - path + 1);
2080 bname[endp - path + 1] = '\0';
2081 return (0);
2082}
2083
2084static void
2085linkmap_add(Obj_Entry *obj)
2086{
2087 struct link_map *l = &obj->linkmap;
2088 struct link_map *prev;
2089
2090 obj->linkmap.l_name = obj->path;
2091 obj->linkmap.l_addr = obj->mapbase;
2092 obj->linkmap.l_ld = obj->dynamic;
2093#ifdef __mips__
2094 /* GDB needs load offset on MIPS to use the symbols */
2095 obj->linkmap.l_offs = obj->relocbase;
2096#endif
2097
2098 if (r_debug.r_map == NULL) {
2099 r_debug.r_map = l;
2100 return;
2101 }
2102
2103 /*
2104 * Scan to the end of the list, but not past the entry for the
2105 * dynamic linker, which we want to keep at the very end.
2106 */
2107 for (prev = r_debug.r_map;
2108 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2109 prev = prev->l_next)
2110 ;
2111
2112 /* Link in the new entry. */
2113 l->l_prev = prev;
2114 l->l_next = prev->l_next;
2115 if (l->l_next != NULL)
2116 l->l_next->l_prev = l;
2117 prev->l_next = l;
2118}
2119
2120static void
2121linkmap_delete(Obj_Entry *obj)
2122{
2123 struct link_map *l = &obj->linkmap;
2124
2125 if (l->l_prev == NULL) {
2126 if ((r_debug.r_map = l->l_next) != NULL)
2127 l->l_next->l_prev = NULL;
2128 return;
2129 }
2130
2131 if ((l->l_prev->l_next = l->l_next) != NULL)
2132 l->l_next->l_prev = l->l_prev;
2133}
2134
2135/*
2136 * Function for the debugger to set a breakpoint on to gain control.
2137 *
2138 * The two parameters allow the debugger to easily find and determine
2139 * what the runtime loader is doing and to whom it is doing it.
2140 *
2141 * When the loadhook trap is hit (r_debug_state, set at program
2142 * initialization), the arguments can be found on the stack:
2143 *
2144 * +8 struct link_map *m
2145 * +4 struct r_debug *rd
2146 * +0 RetAddr
2147 */
2148void
2149r_debug_state(struct r_debug* rd, struct link_map *m)
2150{
2151}
2152
2153/*
2154 * Get address of the pointer variable in the main program.
2155 */
2156static const void **
2157get_program_var_addr(const char *name)
2158{
2159 const Obj_Entry *obj;
2160 unsigned long hash;
2161
2162 hash = elf_hash(name);
2163 for (obj = obj_main; obj != NULL; obj = obj->next) {
2164 const Elf_Sym *def;
2165
2166 if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2167 const void **addr;
2168
2169 addr = (const void **)(obj->relocbase + def->st_value);
2170 return addr;
2171 }
2172 }
2173 return NULL;
2174}
2175
2176/*
2177 * Set a pointer variable in the main program to the given value. This
2178 * is used to set key variables such as "environ" before any of the
2179 * init functions are called.
2180 */
2181static void
2182set_program_var(const char *name, const void *value)
2183{
2184 const void **addr;
2185
2186 if ((addr = get_program_var_addr(name)) != NULL) {
2187 dbg("\"%s\": *%p <-- %p", name, addr, value);
2188 *addr = value;
2189 }
2190}
2191
8ca15ec8
MD
2192/*
2193 * This is a special version of getenv which is far more efficient
2194 * at finding LD_ environment vars.
2195 */
2196static
2197const char *
2198_getenv_ld(const char *id)
2199{
2200 const char *envp;
2201 int i, j;
2202 int idlen = strlen(id);
2203
2204 if (ld_index == LD_ARY_CACHE)
2205 return(getenv(id));
2206 if (ld_index == 0) {
2207 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2208 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2209 ld_ary[j++] = envp;
2210 }
2211 if (j == 0)
2212 ld_ary[j++] = "";
2213 ld_index = j;
2214 }
2215 for (i = ld_index - 1; i >= 0; --i) {
2216 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2217 return(ld_ary[i] + idlen + 1);
2218 }
2219 return(NULL);
2220}
2221
984263bc
MD
2222/*
2223 * Given a symbol name in a referencing object, find the corresponding
2224 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2225 * no definition was found. Returns a pointer to the Obj_Entry of the
2226 * defining object via the reference parameter DEFOBJ_OUT.
2227 */
2228static const Elf_Sym *
2229symlook_default(const char *name, unsigned long hash,
2230 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2231{
2232 DoneList donelist;
2233 const Elf_Sym *def;
2234 const Elf_Sym *symp;
2235 const Obj_Entry *obj;
2236 const Obj_Entry *defobj;
2237 const Objlist_Entry *elm;
2238 def = NULL;
2239 defobj = NULL;
2240 donelist_init(&donelist);
2241
2242 /* Look first in the referencing object if linked symbolically. */
2243 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2244 symp = symlook_obj(name, hash, refobj, in_plt);
2245 if (symp != NULL) {
2246 def = symp;
2247 defobj = refobj;
2248 }
2249 }
2250
2251 /* Search all objects loaded at program start up. */
2252 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2253 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2254 if (symp != NULL &&
2255 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2256 def = symp;
2257 defobj = obj;
2258 }
2259 }
2260
2261 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2262 STAILQ_FOREACH(elm, &list_global, link) {
2263 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2264 break;
2265 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2266 &donelist);
2267 if (symp != NULL &&
2268 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2269 def = symp;
2270 defobj = obj;
2271 }
2272 }
2273
2274 /* Search all dlopened DAGs containing the referencing object. */
2275 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2276 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2277 break;
2278 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2279 &donelist);
2280 if (symp != NULL &&
2281 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2282 def = symp;
2283 defobj = obj;
2284 }
2285 }
2286
2287 /*
2288 * Search the dynamic linker itself, and possibly resolve the
2289 * symbol from there. This is how the application links to
2290 * dynamic linker services such as dlopen. Only the values listed
2291 * in the "exports" array can be resolved from the dynamic linker.
2292 */
2293 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2294 symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2295 if (symp != NULL && is_exported(symp)) {
2296 def = symp;
2297 defobj = &obj_rtld;
2298 }
2299 }
2300
2301 if (def != NULL)
2302 *defobj_out = defobj;
2303 return def;
2304}
2305
2306static const Elf_Sym *
2307symlook_list(const char *name, unsigned long hash, Objlist *objlist,
2308 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2309{
2310 const Elf_Sym *symp;
2311 const Elf_Sym *def;
2312 const Obj_Entry *defobj;
2313 const Objlist_Entry *elm;
2314
2315 def = NULL;
2316 defobj = NULL;
2317 STAILQ_FOREACH(elm, objlist, link) {
2318 if (donelist_check(dlp, elm->obj))
2319 continue;
2320 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2321 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2322 def = symp;
2323 defobj = elm->obj;
2324 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2325 break;
2326 }
2327 }
2328 }
2329 if (def != NULL)
2330 *defobj_out = defobj;
2331 return def;
2332}
2333
2334/*
2335 * Search the symbol table of a single shared object for a symbol of
2336 * the given name. Returns a pointer to the symbol, or NULL if no
2337 * definition was found.
2338 *
2339 * The symbol's hash value is passed in for efficiency reasons; that
2340 * eliminates many recomputations of the hash value.
2341 */
2342const Elf_Sym *
2343symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2344 bool in_plt)
2345{
2346 if (obj->buckets != NULL) {
2347 unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2348
2349 while (symnum != STN_UNDEF) {
2350 const Elf_Sym *symp;
2351 const char *strp;
2352
2353 if (symnum >= obj->nchains)
2354 return NULL; /* Bad object */
2355 symp = obj->symtab + symnum;
2356 strp = obj->strtab + symp->st_name;
2357
2358 if (name[0] == strp[0] && strcmp(name, strp) == 0)
2359 return symp->st_shndx != SHN_UNDEF ||
2360 (!in_plt && symp->st_value != 0 &&
2361 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2362
2363 symnum = obj->chains[symnum];
2364 }
2365 }
2366 return NULL;
2367}
2368
2369static void
2370trace_loaded_objects(Obj_Entry *obj)
2371{
8ca15ec8 2372 const char *fmt1, *fmt2, *fmt, *main_local;
984263bc
MD
2373 int c;
2374
8ca15ec8 2375 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
984263bc
MD
2376 main_local = "";
2377
8ca15ec8 2378 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
984263bc
MD
2379 fmt1 = "\t%o => %p (%x)\n";
2380
8ca15ec8 2381 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
984263bc
MD
2382 fmt2 = "\t%o (%x)\n";
2383
2384 for (; obj; obj = obj->next) {
2385 Needed_Entry *needed;
2386 char *name, *path;
2387 bool is_lib;
2388
2389 for (needed = obj->needed; needed; needed = needed->next) {
2390 if (needed->obj != NULL) {
2391 if (needed->obj->traced)
2392 continue;
2393 needed->obj->traced = true;
2394 path = needed->obj->path;
2395 } else
2396 path = "not found";
2397
2398 name = (char *)obj->strtab + needed->name;
2399 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2400
2401 fmt = is_lib ? fmt1 : fmt2;
2402 while ((c = *fmt++) != '\0') {
2403 switch (c) {
2404 default:
2405 putchar(c);
2406 continue;
2407 case '\\':
2408 switch (c = *fmt) {
2409 case '\0':
2410 continue;
2411 case 'n':
2412 putchar('\n');
2413 break;
2414 case 't':
2415 putchar('\t');
2416 break;
2417 }
2418 break;
2419 case '%':
2420 switch (c = *fmt) {
2421 case '\0':
2422 continue;
2423 case '%':
2424 default:
2425 putchar(c);
2426 break;
2427 case 'A':
2428 printf("%s", main_local);
2429 break;
2430 case 'a':
2431 printf("%s", obj_main->path);
2432 break;
2433 case 'o':
2434 printf("%s", name);
2435 break;
2436#if 0
2437 case 'm':
2438 printf("%d", sodp->sod_major);
2439 break;
2440 case 'n':
2441 printf("%d", sodp->sod_minor);
2442 break;
2443#endif
2444 case 'p':
2445 printf("%s", path);
2446 break;
2447 case 'x':
2448 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2449 break;
2450 }
2451 break;
2452 }
2453 ++fmt;
2454 }
2455 }
2456 }
2457}
2458
2459/*
2460 * Unload a dlopened object and its dependencies from memory and from
2461 * our data structures. It is assumed that the DAG rooted in the
2462 * object has already been unreferenced, and that the object has a
2463 * reference count of 0.
2464 */
2465static void
2466unload_object(Obj_Entry *root)
2467{
2468 Obj_Entry *obj;
2469 Obj_Entry **linkp;
2470
2471 assert(root->refcount == 0);
2472
2473 /*
2474 * Pass over the DAG removing unreferenced objects from
2475 * appropriate lists.
2476 */
2477 unlink_object(root);
2478
2479 /* Unmap all objects that are no longer referenced. */
2480 linkp = &obj_list->next;
2481 while ((obj = *linkp) != NULL) {
2482 if (obj->refcount == 0) {
2483 dbg("unloading \"%s\"", obj->path);
2484 munmap(obj->mapbase, obj->mapsize);
2485 linkmap_delete(obj);
2486 *linkp = obj->next;
2487 obj_count--;
2488 obj_free(obj);
2489 } else
2490 linkp = &obj->next;
2491 }
2492 obj_tail = linkp;
2493}
2494
2495static void
2496unlink_object(Obj_Entry *root)
2497{
2498 const Needed_Entry *needed;
2499 Objlist_Entry *elm;
2500
2501 if (root->refcount == 0) {
2502 /* Remove the object from the RTLD_GLOBAL list. */
2503 objlist_remove(&list_global, root);
2504
2505 /* Remove the object from all objects' DAG lists. */
2506 STAILQ_FOREACH(elm, &root->dagmembers , link)
2507 objlist_remove(&elm->obj->dldags, root);
2508 }
2509
2510 for (needed = root->needed; needed != NULL; needed = needed->next)
2511 if (needed->obj != NULL)
2512 unlink_object(needed->obj);
2513}
2514
2515static void
2516unref_dag(Obj_Entry *root)
2517{
2518 const Needed_Entry *needed;
2519
2520 if (root->refcount == 0)
2521 return;
2522 root->refcount--;
2523 if (root->refcount == 0)
2524 for (needed = root->needed; needed != NULL; needed = needed->next)
2525 if (needed->obj != NULL)
2526 unref_dag(needed->obj);
2527}