1 #define _GNU_SOURCE
2 #define SYSCALL_NO_TLS 1
3 #include <stdlib.h>
4 #include <stdarg.h>
5 #include <stddef.h>
6 #include <string.h>
7 #include <unistd.h>
8 #include <stdint.h>
9 #include <elf.h>
10 #include <sys/mman.h>
11 #include <limits.h>
12 #include <fcntl.h>
13 #include <sys/stat.h>
14 #include <errno.h>
15 #include <link.h>
16 #include <setjmp.h>
17 #include <pthread.h>
18 #include <ctype.h>
19 #include <dlfcn.h>
20 #include <semaphore.h>
21 #include <sys/membarrier.h>
22 #include "pthread_impl.h"
23 #include "fork_impl.h"
24 #include "dynlink.h"
25
26 static size_t ldso_page_size;
27 #ifndef PAGE_SIZE
28 #define PAGE_SIZE ldso_page_size
29 #endif
30
31 #include "libc.h"
32
33 #define STRINGIFY(x) __STRINGIFY(x)
34 #define __STRINGIFY(x) #x
35
36 #define malloc __libc_malloc
37 #define calloc __libc_calloc
38 #define realloc __libc_realloc
39 #define free __libc_free
40
41 static void error_impl(const char *, ...);
42 static void error_noop(const char *, ...);
43 static void (*error)(const char *, ...) = error_noop;
44
45 #define MAXP2(a,b) (-(-(a)&-(b)))
46 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
47
48 #define container_of(p,t,m) ((t*)((char *)(p)-offsetof(t,m)))
49 #define countof(a) ((sizeof (a))/(sizeof (a)[0]))
50
51 struct debug {
52 int ver;
53 void *head;
54 void (*bp)(void);
55 int state;
56 void *base;
57 };
58
59 struct td_index {
60 size_t args[2];
61 struct td_index *next;
62 };
63
64 struct dso {
65 #if DL_FDPIC
66 struct fdpic_loadmap *loadmap;
67 #else
68 unsigned char *base;
69 #endif
70 char *name;
71 size_t *dynv;
72 struct dso *next, *prev;
73
74 int elfmachine;
75 int elfclass;
76 Phdr *phdr;
77 int phnum;
78 size_t phentsize;
79 Sym *syms;
80 Elf_Symndx *hashtab;
81 uint32_t *ghashtab;
82 int16_t *versym;
83 char *strings;
84 struct dso *syms_next, *lazy_next;
85 size_t *lazy, lazy_cnt;
86 unsigned char *map;
87 size_t map_len;
88 dev_t dev;
89 ino_t ino;
90 char relocated;
91 char constructed;
92 char kernel_mapped;
93 char mark;
94 char bfs_built;
95 char runtime_loaded;
96 struct dso **deps, *needed_by;
97 size_t ndeps_direct;
98 size_t next_dep;
99 pthread_t ctor_visitor;
100 char *rpath_orig, *rpath;
101 struct tls_module tls;
102 size_t tls_id;
103 size_t relro_start, relro_end;
104 uintptr_t *new_dtv;
105 unsigned char *new_tls;
106 struct td_index *td_index;
107 struct dso *fini_next;
108 char *shortname;
109 #if DL_FDPIC
110 unsigned char *base;
111 #else
112 struct fdpic_loadmap *loadmap;
113 #endif
114 struct funcdesc {
115 void *addr;
116 size_t *got;
117 } *funcdescs;
118 size_t *got;
119 char buf[];
120 };
121
122 struct symdef {
123 Sym *sym;
124 struct dso *dso;
125 };
126
127 typedef void (*stage3_func)(size_t *, size_t *);
128
129 static struct builtin_tls {
130 char c;
131 struct pthread pt;
132 void *space[16];
133 } builtin_tls[1];
134 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
135
136 #define ADDEND_LIMIT 4096
137 static size_t *saved_addends, *apply_addends_to;
138
139 static struct dso ldso;
140 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
141 static char *env_path, *sys_path;
142 static unsigned long long gencnt;
143 static int runtime;
144 static int ldd_mode;
145 static int ldso_fail;
146 static int noload;
147 static int shutting_down;
148 static jmp_buf *rtld_fail;
149 static pthread_rwlock_t lock;
150 static struct debug debug;
151 static struct tls_module *tls_tail;
152 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
153 static size_t static_tls_cnt;
154 static pthread_mutex_t init_fini_lock;
155 static pthread_cond_t ctor_cond;
156 static struct dso *builtin_deps[2];
157 static struct dso *const no_deps[1];
158 static struct dso *builtin_ctor_queue[4];
159 static struct dso **main_ctor_queue;
160 static struct fdpic_loadmap *app_loadmap;
161 static struct fdpic_dummy_loadmap app_dummy_loadmap;
162
163 struct debug *_dl_debug_addr = &debug;
164 static void (*exe_dl_debug_state)(void) = 0;
165
166 extern weak hidden char __ehdr_start[];
167
168 extern hidden int __malloc_replaced;
169
170 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
171
172 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
173
174 weak_alias(__init_array_start, __init_array_end);
175 weak_alias(__fini_array_start, __fini_array_end);
176
dl_strcmp(const char * l,const char * r)177 static int dl_strcmp(const char *l, const char *r)
178 {
179 for (; *l==*r && *l; l++, r++);
180 return *(unsigned char *)l - *(unsigned char *)r;
181 }
182 #define strcmp(l,r) dl_strcmp(l,r)
183
184 /* Compute load address for a virtual address in a given dso. */
185 #if DL_FDPIC
laddr(const struct dso * p,size_t v)186 static void *laddr(const struct dso *p, size_t v)
187 {
188 size_t j=0;
189 if (!p->loadmap) return p->base + v;
190 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
191 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
192 }
laddr_pg(const struct dso * p,size_t v)193 static void *laddr_pg(const struct dso *p, size_t v)
194 {
195 size_t j=0;
196 size_t pgsz = PAGE_SIZE;
197 if (!p->loadmap) return p->base + v;
198 for (j=0; ; j++) {
199 size_t a = p->loadmap->segs[j].p_vaddr;
200 size_t b = a + p->loadmap->segs[j].p_memsz;
201 a &= -pgsz;
202 b += pgsz-1;
203 b &= -pgsz;
204 if (v-a<b-a) break;
205 }
206 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
207 }
fdbarrier(void * p)208 static void (*fdbarrier(void *p))()
209 {
210 void (*fd)();
211 __asm__("" : "=r"(fd) : "0"(p));
212 return fd;
213 }
214 #define fpaddr(p, v) fdbarrier((&(struct funcdesc){ \
215 laddr(p, v), (p)->got }))
216 #else
217 #define laddr(p, v) (void *)((p)->base + (v))
218 #define laddr_pg(p, v) laddr(p, v)
219 #define fpaddr(p, v) ((void (*)())laddr(p, v))
220 #endif
221
decode_vec(size_t * v,size_t * a,size_t cnt)222 static void decode_vec(size_t *v, size_t *a, size_t cnt)
223 {
224 size_t i;
225 for (i=0; i<cnt; i++) a[i] = 0;
226 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
227 if (v[0] < 8*sizeof(long))
228 a[0] |= 1UL<<v[0];
229 a[v[0]] = v[1];
230 }
231 }
232
search_vec(size_t * v,size_t * r,size_t key)233 static int search_vec(size_t *v, size_t *r, size_t key)
234 {
235 for (; v[0]!=key; v+=2)
236 if (!v[0]) return 0;
237 *r = v[1];
238 return 1;
239 }
240
sysv_hash(const char * s0)241 static uint32_t sysv_hash(const char *s0)
242 {
243 const unsigned char *s = (void *)s0;
244 uint_fast32_t h = 0;
245 while (*s) {
246 h = 16*h + *s++;
247 h ^= h>>24 & 0xf0;
248 }
249 return h & 0xfffffff;
250 }
251
gnu_hash(const char * s0)252 static uint32_t gnu_hash(const char *s0)
253 {
254 const unsigned char *s = (void *)s0;
255 uint_fast32_t h = 5381;
256 for (; *s; s++)
257 h += h*32 + *s;
258 return h;
259 }
260
sysv_lookup(const char * s,uint32_t h,struct dso * dso)261 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
262 {
263 size_t i;
264 Sym *syms = dso->syms;
265 Elf_Symndx *hashtab = dso->hashtab;
266 char *strings = dso->strings;
267 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
268 if ((!dso->versym || dso->versym[i] >= 0)
269 && (!strcmp(s, strings+syms[i].st_name)))
270 return syms+i;
271 }
272 return 0;
273 }
274
gnu_lookup(uint32_t h1,uint32_t * hashtab,struct dso * dso,const char * s)275 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
276 {
277 uint32_t nbuckets = hashtab[0];
278 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
279 uint32_t i = buckets[h1 % nbuckets];
280
281 if (!i) return 0;
282
283 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
284
285 for (h1 |= 1; ; i++) {
286 uint32_t h2 = *hashval++;
287 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
288 && !strcmp(s, dso->strings + dso->syms[i].st_name))
289 return dso->syms+i;
290 if (h2 & 1) break;
291 }
292
293 return 0;
294 }
295
gnu_lookup_filtered(uint32_t h1,uint32_t * hashtab,struct dso * dso,const char * s,uint32_t fofs,size_t fmask)296 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
297 {
298 const size_t *bloomwords = (const void *)(hashtab+4);
299 size_t f = bloomwords[fofs & (hashtab[2]-1)];
300 if (!(f & fmask)) return 0;
301
302 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
303 if (!(f & 1)) return 0;
304
305 return gnu_lookup(h1, hashtab, dso, s);
306 }
307
308 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
309 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
310
311 #ifndef ARCH_SYM_REJECT_UND
312 #define ARCH_SYM_REJECT_UND(s) 0
313 #endif
314
315 #if defined(__GNUC__)
316 __attribute__((always_inline))
317 #endif
find_sym2(struct dso * dso,const char * s,int need_def,int use_deps)318 static inline struct symdef find_sym2(struct dso *dso, const char *s, int need_def, int use_deps)
319 {
320 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
321 size_t ghm = 1ul << gh % (8*sizeof(size_t));
322 struct symdef def = {0};
323 struct dso **deps = use_deps ? dso->deps : 0;
324 for (; dso; dso=use_deps ? *deps++ : dso->syms_next) {
325 Sym *sym;
326 if ((ght = dso->ghashtab)) {
327 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
328 } else {
329 if (!h) h = sysv_hash(s);
330 sym = sysv_lookup(s, h, dso);
331 }
332 if (!sym) continue;
333 if (!sym->st_shndx)
334 if (need_def || (sym->st_info&0xf) == STT_TLS
335 || ARCH_SYM_REJECT_UND(sym))
336 continue;
337 if (!sym->st_value)
338 if ((sym->st_info&0xf) != STT_TLS)
339 continue;
340 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
341 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
342 def.sym = sym;
343 def.dso = dso;
344 break;
345 }
346 return def;
347 }
348
find_sym(struct dso * dso,const char * s,int need_def)349 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
350 {
351 return find_sym2(dso, s, need_def, 0);
352 }
353
get_lfs64(const char * name)354 static struct symdef get_lfs64(const char *name)
355 {
356 const char *p;
357 static const char lfs64_list[] =
358 "aio_cancel\0aio_error\0aio_fsync\0aio_read\0aio_return\0"
359 "aio_suspend\0aio_write\0alphasort\0creat\0fallocate\0"
360 "fgetpos\0fopen\0freopen\0fseeko\0fsetpos\0fstat\0"
361 "fstatat\0fstatfs\0fstatvfs\0ftello\0ftruncate\0ftw\0"
362 "getdents\0getrlimit\0glob\0globfree\0lio_listio\0"
363 "lockf\0lseek\0lstat\0mkostemp\0mkostemps\0mkstemp\0"
364 "mkstemps\0mmap\0nftw\0open\0openat\0posix_fadvise\0"
365 "posix_fallocate\0pread\0preadv\0prlimit\0pwrite\0"
366 "pwritev\0readdir\0scandir\0sendfile\0setrlimit\0"
367 "stat\0statfs\0statvfs\0tmpfile\0truncate\0versionsort\0"
368 "__fxstat\0__fxstatat\0__lxstat\0__xstat\0";
369 size_t l;
370 char buf[16];
371 for (l=0; name[l]; l++) {
372 if (l >= sizeof buf) goto nomatch;
373 buf[l] = name[l];
374 }
375 if (!strcmp(name, "readdir64_r"))
376 return find_sym(&ldso, "readdir_r", 1);
377 if (l<2 || name[l-2]!='6' || name[l-1]!='4')
378 goto nomatch;
379 buf[l-=2] = 0;
380 for (p=lfs64_list; *p; p++) {
381 if (!strcmp(buf, p)) return find_sym(&ldso, buf, 1);
382 while (*p) p++;
383 }
384 nomatch:
385 return (struct symdef){ 0 };
386 }
387
do_relocs(struct dso * dso,size_t * rel,size_t rel_size,size_t stride)388 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
389 {
390 unsigned char *base = dso->base;
391 Sym *syms = dso->syms;
392 char *strings = dso->strings;
393 Sym *sym;
394 const char *name;
395 void *ctx;
396 int type;
397 int sym_index;
398 struct symdef def;
399 size_t *reloc_addr;
400 size_t sym_val;
401 size_t tls_val;
402 size_t addend;
403 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
404
405 if (dso == &ldso) {
406 /* Only ldso's REL table needs addend saving/reuse. */
407 if (rel == apply_addends_to)
408 reuse_addends = 1;
409 skip_relative = 1;
410 }
411
412 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
413 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
414 type = R_TYPE(rel[1]);
415 if (type == REL_NONE) continue;
416 reloc_addr = laddr(dso, rel[0]);
417
418 if (stride > 2) {
419 addend = rel[2];
420 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
421 addend = 0;
422 } else if (reuse_addends) {
423 /* Save original addend in stage 2 where the dso
424 * chain consists of just ldso; otherwise read back
425 * saved addend since the inline one was clobbered. */
426 if (head==&ldso)
427 saved_addends[save_slot] = *reloc_addr;
428 addend = saved_addends[save_slot++];
429 } else {
430 addend = *reloc_addr;
431 }
432
433 sym_index = R_SYM(rel[1]);
434 if (sym_index) {
435 sym = syms + sym_index;
436 name = strings + sym->st_name;
437 ctx = type==REL_COPY ? head->syms_next : head;
438 def = (sym->st_info>>4) == STB_LOCAL
439 ? (struct symdef){ .dso = dso, .sym = sym }
440 : find_sym(ctx, name, type==REL_PLT);
441 if (!def.sym) def = get_lfs64(name);
442 if (!def.sym && (sym->st_shndx != SHN_UNDEF
443 || sym->st_info>>4 != STB_WEAK)) {
444 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
445 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
446 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
447 dso->lazy[3*dso->lazy_cnt+2] = addend;
448 dso->lazy_cnt++;
449 continue;
450 }
451 error("Error relocating %s: %s: symbol not found",
452 dso->name, name);
453 if (runtime) longjmp(*rtld_fail, 1);
454 continue;
455 }
456 } else {
457 sym = 0;
458 def.sym = 0;
459 def.dso = dso;
460 }
461
462 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
463 tls_val = def.sym ? def.sym->st_value : 0;
464
465 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
466 && def.dso && def.dso->tls_id > static_tls_cnt) {
467 error("Error relocating %s: %s: initial-exec TLS "
468 "resolves to dynamic definition in %s",
469 dso->name, name, def.dso->name);
470 longjmp(*rtld_fail, 1);
471 }
472
473 switch(type) {
474 case REL_OFFSET:
475 addend -= (size_t)reloc_addr;
476 case REL_SYMBOLIC:
477 case REL_GOT:
478 case REL_PLT:
479 *reloc_addr = sym_val + addend;
480 break;
481 case REL_USYMBOLIC:
482 memcpy(reloc_addr, &(size_t){sym_val + addend}, sizeof(size_t));
483 break;
484 case REL_RELATIVE:
485 *reloc_addr = (size_t)base + addend;
486 break;
487 case REL_SYM_OR_REL:
488 if (sym) *reloc_addr = sym_val + addend;
489 else *reloc_addr = (size_t)base + addend;
490 break;
491 case REL_COPY:
492 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
493 break;
494 case REL_OFFSET32:
495 *(uint32_t *)reloc_addr = sym_val + addend
496 - (size_t)reloc_addr;
497 break;
498 case REL_FUNCDESC:
499 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
500 + (def.sym - def.dso->syms)) : 0;
501 break;
502 case REL_FUNCDESC_VAL:
503 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
504 else *reloc_addr = sym_val;
505 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
506 break;
507 case REL_DTPMOD:
508 *reloc_addr = def.dso->tls_id;
509 break;
510 case REL_DTPOFF:
511 *reloc_addr = tls_val + addend - DTP_OFFSET;
512 break;
513 #ifdef TLS_ABOVE_TP
514 case REL_TPOFF:
515 *reloc_addr = (def.dso ? tls_val + def.dso->tls.offset + TPOFF_K : 0) + addend;
516 break;
517 #else
518 case REL_TPOFF:
519 *reloc_addr = (def.dso ? tls_val - def.dso->tls.offset : 0) + addend;
520 break;
521 case REL_TPOFF_NEG:
522 *reloc_addr = (def.dso ? def.dso->tls.offset - tls_val : 0) + addend;
523 break;
524 #endif
525 case REL_TLSDESC:
526 if (stride<3) addend = reloc_addr[!TLSDESC_BACKWARDS];
527 if (def.dso->tls_id > static_tls_cnt) {
528 struct td_index *new = malloc(sizeof *new);
529 if (!new) {
530 error(
531 "Error relocating %s: cannot allocate TLSDESC for %s",
532 dso->name, sym ? name : "(local)" );
533 longjmp(*rtld_fail, 1);
534 }
535 new->next = dso->td_index;
536 dso->td_index = new;
537 new->args[0] = def.dso->tls_id;
538 new->args[1] = tls_val + addend - DTP_OFFSET;
539 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
540 reloc_addr[1] = (size_t)new;
541 } else {
542 reloc_addr[0] = (size_t)__tlsdesc_static;
543 #ifdef TLS_ABOVE_TP
544 reloc_addr[1] = tls_val + def.dso->tls.offset
545 + TPOFF_K + addend;
546 #else
547 reloc_addr[1] = tls_val - def.dso->tls.offset
548 + addend;
549 #endif
550 }
551 /* Some archs (32-bit ARM at least) invert the order of
552 * the descriptor members. Fix them up here. */
553 if (TLSDESC_BACKWARDS) {
554 size_t tmp = reloc_addr[0];
555 reloc_addr[0] = reloc_addr[1];
556 reloc_addr[1] = tmp;
557 }
558 break;
559 default:
560 error("Error relocating %s: unsupported relocation type %d",
561 dso->name, type);
562 if (runtime) longjmp(*rtld_fail, 1);
563 continue;
564 }
565 }
566 }
567
do_relr_relocs(struct dso * dso,size_t * relr,size_t relr_size)568 static void do_relr_relocs(struct dso *dso, size_t *relr, size_t relr_size)
569 {
570 if (dso == &ldso) return; /* self-relocation was done in _dlstart */
571 unsigned char *base = dso->base;
572 size_t *reloc_addr;
573 for (; relr_size; relr++, relr_size-=sizeof(size_t))
574 if ((relr[0]&1) == 0) {
575 reloc_addr = laddr(dso, relr[0]);
576 *reloc_addr++ += (size_t)base;
577 } else {
578 int i = 0;
579 for (size_t bitmap=relr[0]; (bitmap>>=1); i++)
580 if (bitmap&1)
581 reloc_addr[i] += (size_t)base;
582 reloc_addr += 8*sizeof(size_t)-1;
583 }
584 }
585
redo_lazy_relocs()586 static void redo_lazy_relocs()
587 {
588 struct dso *p = lazy_head, *next;
589 lazy_head = 0;
590 for (; p; p=next) {
591 next = p->lazy_next;
592 size_t size = p->lazy_cnt*3*sizeof(size_t);
593 p->lazy_cnt = 0;
594 do_relocs(p, p->lazy, size, 3);
595 if (p->lazy_cnt) {
596 p->lazy_next = lazy_head;
597 lazy_head = p;
598 } else {
599 free(p->lazy);
600 p->lazy = 0;
601 p->lazy_next = 0;
602 }
603 }
604 }
605
606 /* A huge hack: to make up for the wastefulness of shared libraries
607 * needing at least a page of dirty memory even if they have no global
608 * data, we reclaim the gaps at the beginning and end of writable maps
609 * and "donate" them to the heap. */
610
reclaim(struct dso * dso,size_t start,size_t end)611 static void reclaim(struct dso *dso, size_t start, size_t end)
612 {
613 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
614 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
615 if (start >= end) return;
616 char *base = laddr_pg(dso, start);
617 __malloc_donate(base, base+(end-start));
618 }
619
reclaim_gaps(struct dso * dso)620 static void reclaim_gaps(struct dso *dso)
621 {
622 Phdr *ph = dso->phdr;
623 size_t phcnt = dso->phnum;
624
625 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
626 if (ph->p_type!=PT_LOAD) continue;
627 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
628 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
629 reclaim(dso, ph->p_vaddr+ph->p_memsz,
630 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
631 }
632 }
633
read_loop(int fd,void * p,size_t n)634 static ssize_t read_loop(int fd, void *p, size_t n)
635 {
636 for (size_t i=0; i<n; ) {
637 ssize_t l = read(fd, (char *)p+i, n-i);
638 if (l<0) {
639 if (errno==EINTR) continue;
640 else return -1;
641 }
642 if (l==0) return i;
643 i += l;
644 }
645 return n;
646 }
647
mmap_fixed(void * p,size_t n,int prot,int flags,int fd,off_t off)648 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
649 {
650 static int no_map_fixed;
651 char *q;
652 if (!n) return p;
653 if (!no_map_fixed) {
654 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
655 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
656 return q;
657 no_map_fixed = 1;
658 }
659 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
660 if (flags & MAP_ANONYMOUS) {
661 memset(p, 0, n);
662 return p;
663 }
664 ssize_t r;
665 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
666 for (q=p; n; q+=r, off+=r, n-=r) {
667 r = read(fd, q, n);
668 if (r < 0 && errno != EINTR) return MAP_FAILED;
669 if (!r) {
670 memset(q, 0, n);
671 break;
672 }
673 }
674 return p;
675 }
676
unmap_library(struct dso * dso)677 static void unmap_library(struct dso *dso)
678 {
679 if (dso->loadmap) {
680 size_t i;
681 for (i=0; i<dso->loadmap->nsegs; i++) {
682 if (!dso->loadmap->segs[i].p_memsz)
683 continue;
684 munmap((void *)dso->loadmap->segs[i].addr,
685 dso->loadmap->segs[i].p_memsz);
686 }
687 free(dso->loadmap);
688 } else if (dso->map && dso->map_len) {
689 munmap(dso->map, dso->map_len);
690 }
691 }
692
verify_elf_magic(const Ehdr * eh)693 static int verify_elf_magic(const Ehdr* eh) {
694 return eh->e_ident[0] == ELFMAG0 &&
695 eh->e_ident[1] == ELFMAG1 &&
696 eh->e_ident[2] == ELFMAG2 &&
697 eh->e_ident[3] == ELFMAG3;
698 }
699
700 /* Verifies that an elf header's machine and class match the loader */
verify_elf_arch(const Ehdr * eh)701 static int verify_elf_arch(const Ehdr* eh) {
702 return eh->e_machine == ldso.elfmachine &&
703 eh->e_ident[EI_CLASS] == ldso.elfclass;
704 }
705
map_library(int fd,struct dso * dso)706 static void *map_library(int fd, struct dso *dso)
707 {
708 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
709 void *allocated_buf=0;
710 size_t phsize;
711 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
712 size_t this_min, this_max;
713 size_t nsegs = 0;
714 off_t off_start;
715 Ehdr *eh;
716 Phdr *ph, *ph0;
717 unsigned prot;
718 unsigned char *map=MAP_FAILED, *base;
719 size_t dyn=0;
720 size_t tls_image=0;
721 size_t i;
722
723 ssize_t l = read(fd, buf, sizeof buf);
724 eh = buf;
725 if (l<0) return 0;
726 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
727 goto noexec;
728 if (!verify_elf_magic(eh)) goto noexec;
729 if (!verify_elf_arch(eh)) goto noexec;
730 dso->elfmachine = eh->e_machine;
731 dso->elfclass = eh->e_ident[EI_CLASS];
732 phsize = eh->e_phentsize * eh->e_phnum;
733 if (phsize > sizeof buf - sizeof *eh) {
734 allocated_buf = malloc(phsize);
735 if (!allocated_buf) return 0;
736 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
737 if (l < 0) goto error;
738 if (l != phsize) goto noexec;
739 ph = ph0 = allocated_buf;
740 } else if (eh->e_phoff + phsize > l) {
741 l = pread(fd, buf+1, phsize, eh->e_phoff);
742 if (l < 0) goto error;
743 if (l != phsize) goto noexec;
744 ph = ph0 = (void *)(buf + 1);
745 } else {
746 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
747 }
748 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
749 if (ph->p_type == PT_DYNAMIC) {
750 dyn = ph->p_vaddr;
751 } else if (ph->p_type == PT_TLS) {
752 tls_image = ph->p_vaddr;
753 dso->tls.align = ph->p_align;
754 dso->tls.len = ph->p_filesz;
755 dso->tls.size = ph->p_memsz;
756 } else if (ph->p_type == PT_GNU_RELRO) {
757 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
758 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
759 } else if (ph->p_type == PT_GNU_STACK) {
760 if (!runtime && ph->p_memsz > __default_stacksize) {
761 __default_stacksize =
762 ph->p_memsz < DEFAULT_STACK_MAX ?
763 ph->p_memsz : DEFAULT_STACK_MAX;
764 }
765 }
766 if (ph->p_type != PT_LOAD) continue;
767 nsegs++;
768 if (ph->p_vaddr < addr_min) {
769 addr_min = ph->p_vaddr;
770 off_start = ph->p_offset;
771 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
772 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
773 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
774 }
775 if (ph->p_vaddr+ph->p_memsz > addr_max) {
776 addr_max = ph->p_vaddr+ph->p_memsz;
777 }
778 }
779 if (!dyn) goto noexec;
780 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
781 dso->loadmap = calloc(1, sizeof *dso->loadmap
782 + nsegs * sizeof *dso->loadmap->segs);
783 if (!dso->loadmap) goto error;
784 dso->loadmap->nsegs = nsegs;
785 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
786 if (ph->p_type != PT_LOAD) continue;
787 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
788 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
789 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
790 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
791 prot, MAP_PRIVATE,
792 fd, ph->p_offset & -PAGE_SIZE);
793 if (map == MAP_FAILED) {
794 unmap_library(dso);
795 goto error;
796 }
797 dso->loadmap->segs[i].addr = (size_t)map +
798 (ph->p_vaddr & PAGE_SIZE-1);
799 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
800 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
801 i++;
802 if (prot & PROT_WRITE) {
803 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
804 + ph->p_filesz;
805 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
806 size_t pgend = brk + ph->p_memsz - ph->p_filesz
807 + PAGE_SIZE-1 & -PAGE_SIZE;
808 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
809 pgend-pgbrk, prot,
810 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
811 -1, off_start) == MAP_FAILED)
812 goto error;
813 memset(map + brk, 0, pgbrk-brk);
814 }
815 }
816 map = (void *)dso->loadmap->segs[0].addr;
817 map_len = 0;
818 goto done_mapping;
819 }
820 addr_max += PAGE_SIZE-1;
821 addr_max &= -PAGE_SIZE;
822 addr_min &= -PAGE_SIZE;
823 off_start &= -PAGE_SIZE;
824 map_len = addr_max - addr_min + off_start;
825 /* The first time, we map too much, possibly even more than
826 * the length of the file. This is okay because we will not
827 * use the invalid part; we just need to reserve the right
828 * amount of virtual address space to map over later. */
829 map = DL_NOMMU_SUPPORT
830 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
831 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
832 : mmap((void *)addr_min, map_len, prot,
833 MAP_PRIVATE, fd, off_start);
834 if (map==MAP_FAILED) goto error;
835 dso->map = map;
836 dso->map_len = map_len;
837 /* If the loaded file is not relocatable and the requested address is
838 * not available, then the load operation must fail. */
839 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
840 errno = EBUSY;
841 goto error;
842 }
843 base = map - addr_min;
844 dso->phdr = 0;
845 dso->phnum = 0;
846 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
847 if (ph->p_type != PT_LOAD) continue;
848 /* Check if the programs headers are in this load segment, and
849 * if so, record the address for use by dl_iterate_phdr. */
850 if (!dso->phdr && eh->e_phoff >= ph->p_offset
851 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
852 dso->phdr = (void *)(base + ph->p_vaddr
853 + (eh->e_phoff-ph->p_offset));
854 dso->phnum = eh->e_phnum;
855 dso->phentsize = eh->e_phentsize;
856 }
857 this_min = ph->p_vaddr & -PAGE_SIZE;
858 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
859 off_start = ph->p_offset & -PAGE_SIZE;
860 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
861 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
862 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
863 /* Reuse the existing mapping for the lowest-address LOAD */
864 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
865 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
866 goto error;
867 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
868 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
869 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
870 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
871 if (pgbrk-(size_t)base < this_max && mmap_fixed((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
872 goto error;
873 }
874 }
875 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
876 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
877 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
878 && errno != ENOSYS)
879 goto error;
880 break;
881 }
882 done_mapping:
883 dso->base = base;
884 dso->dynv = laddr(dso, dyn);
885 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
886 free(allocated_buf);
887 return map;
888 noexec:
889 errno = ENOEXEC;
890 error:
891 if (map!=MAP_FAILED) unmap_library(dso);
892 free(allocated_buf);
893 return 0;
894 }
895
path_open_library(const char * name,const char * s,char * buf,size_t buf_size)896 static int path_open_library(const char *name, const char *s, char *buf, size_t buf_size)
897 {
898 size_t l;
899 int fd;
900 const char *p;
901 for (;;) {
902 s += strspn(s, ":\n");
903 p = s;
904 l = strcspn(s, ":\n");
905 if (l-1 >= INT_MAX) return -1;
906 s += l;
907 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, p, name) < buf_size) {
908 fd = open(buf, O_RDONLY|O_CLOEXEC);
909 if (fd < 0) {
910 switch (errno) {
911 case ENOENT:
912 case ENOTDIR:
913 case EACCES:
914 case ENAMETOOLONG:
915 /* Keep searching in path list. */
916 continue;
917 default:
918 /* Any negative value but -1 will
919 * inhibit further path search in
920 * load_library. */
921 return -2;
922 }
923 }
924 Ehdr eh;
925 ssize_t n = pread(fd, &eh, sizeof eh, 0);
926 /* If the elf file is invalid return -2 to inhibit
927 * further path search in load_library. */
928 if (n < 0 ||
929 n != sizeof eh ||
930 !verify_elf_magic(&eh)) {
931 close(fd);
932 return -2;
933 }
934 /* If the elf file has a valid header but is for the
935 * wrong architecture ignore it and keep searching the
936 * path list. */
937 if (!verify_elf_arch(&eh)) {
938 close(fd);
939 continue;
940 }
941 return fd;
942 }
943 }
944 }
945
fixup_rpath(struct dso * p,char * buf,size_t buf_size)946 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
947 {
948 size_t n, l;
949 const char *s, *t, *origin;
950 char *d;
951 if (p->rpath || !p->rpath_orig) return 0;
952 if (!strchr(p->rpath_orig, '$')) {
953 p->rpath = p->rpath_orig;
954 return 0;
955 }
956 n = 0;
957 s = p->rpath_orig;
958 while ((t=strchr(s, '$'))) {
959 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
960 return 0;
961 s = t+1;
962 n++;
963 }
964 if (n > SSIZE_MAX/PATH_MAX) return 0;
965
966 if (p->kernel_mapped) {
967 /* $ORIGIN searches cannot be performed for the main program
968 * when it is suid/sgid/AT_SECURE. This is because the
969 * pathname is under the control of the caller of execve.
970 * For libraries, however, $ORIGIN can be processed safely
971 * since the library's pathname came from a trusted source
972 * (either system paths or a call to dlopen). */
973 if (libc.secure)
974 return 0;
975 l = readlink("/proc/self/exe", buf, buf_size);
976 if (l == -1) switch (errno) {
977 case ENOENT:
978 case ENOTDIR:
979 case EACCES:
980 return 0;
981 default:
982 return -1;
983 }
984 if (l >= buf_size)
985 return 0;
986 buf[l] = 0;
987 origin = buf;
988 } else {
989 origin = p->name;
990 }
991 t = strrchr(origin, '/');
992 if (t) {
993 l = t-origin;
994 } else {
995 /* Normally p->name will always be an absolute or relative
996 * pathname containing at least one '/' character, but in the
997 * case where ldso was invoked as a command to execute a
998 * program in the working directory, app.name may not. Fix. */
999 origin = ".";
1000 l = 1;
1001 }
1002 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
1003 if (libc.secure && *origin != '/')
1004 return 0;
1005 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
1006 if (!p->rpath) return -1;
1007
1008 d = p->rpath;
1009 s = p->rpath_orig;
1010 while ((t=strchr(s, '$'))) {
1011 memcpy(d, s, t-s);
1012 d += t-s;
1013 memcpy(d, origin, l);
1014 d += l;
1015 /* It was determined previously that the '$' is followed
1016 * either by "ORIGIN" or "{ORIGIN}". */
1017 s = t + 7 + 2*(t[1]=='{');
1018 }
1019 strcpy(d, s);
1020 return 0;
1021 }
1022
decode_dyn(struct dso * p)1023 static void decode_dyn(struct dso *p)
1024 {
1025 size_t dyn[DYN_CNT];
1026 decode_vec(p->dynv, dyn, DYN_CNT);
1027 p->syms = laddr(p, dyn[DT_SYMTAB]);
1028 p->strings = laddr(p, dyn[DT_STRTAB]);
1029 if (dyn[0]&(1<<DT_HASH))
1030 p->hashtab = laddr(p, dyn[DT_HASH]);
1031 if (dyn[0]&(1<<DT_RPATH))
1032 p->rpath_orig = p->strings + dyn[DT_RPATH];
1033 if (dyn[0]&(1<<DT_RUNPATH))
1034 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
1035 if (dyn[0]&(1<<DT_PLTGOT))
1036 p->got = laddr(p, dyn[DT_PLTGOT]);
1037 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
1038 p->ghashtab = laddr(p, *dyn);
1039 if (search_vec(p->dynv, dyn, DT_VERSYM))
1040 p->versym = laddr(p, *dyn);
1041 }
1042
count_syms(struct dso * p)1043 static size_t count_syms(struct dso *p)
1044 {
1045 if (p->hashtab) return p->hashtab[1];
1046
1047 size_t nsym, i;
1048 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1049 uint32_t *hashval;
1050 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1051 if (buckets[i] > nsym)
1052 nsym = buckets[i];
1053 }
1054 if (nsym) {
1055 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
1056 do nsym++;
1057 while (!(*hashval++ & 1));
1058 }
1059 return nsym;
1060 }
1061
dl_mmap(size_t n)1062 static void *dl_mmap(size_t n)
1063 {
1064 void *p;
1065 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
1066 #ifdef SYS_mmap2
1067 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
1068 #else
1069 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
1070 #endif
1071 return (unsigned long)p > -4096UL ? 0 : p;
1072 }
1073
makefuncdescs(struct dso * p)1074 static void makefuncdescs(struct dso *p)
1075 {
1076 static int self_done;
1077 size_t nsym = count_syms(p);
1078 size_t i, size = nsym * sizeof(*p->funcdescs);
1079
1080 if (!self_done) {
1081 p->funcdescs = dl_mmap(size);
1082 self_done = 1;
1083 } else {
1084 p->funcdescs = malloc(size);
1085 }
1086 if (!p->funcdescs) {
1087 if (!runtime) a_crash();
1088 error("Error allocating function descriptors for %s", p->name);
1089 longjmp(*rtld_fail, 1);
1090 }
1091 for (i=0; i<nsym; i++) {
1092 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
1093 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
1094 p->funcdescs[i].got = p->got;
1095 } else {
1096 p->funcdescs[i].addr = 0;
1097 p->funcdescs[i].got = 0;
1098 }
1099 }
1100 }
1101
load_library(const char * name,struct dso * needed_by)1102 static struct dso *load_library(const char *name, struct dso *needed_by)
1103 {
1104 char buf[2*NAME_MAX+2];
1105 const char *pathname;
1106 unsigned char *map;
1107 struct dso *p, temp_dso = {0};
1108 int fd;
1109 struct stat st;
1110 size_t alloc_size;
1111 int n_th = 0;
1112 int is_self = 0;
1113
1114 if (!*name) {
1115 errno = EINVAL;
1116 return 0;
1117 }
1118
1119 /* Catch and block attempts to reload the implementation itself */
1120 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
1121 static const char reserved[] =
1122 "c.c_musl.pthread.rt.m.dl.util.xnet.";
1123 const char *rp, *next;
1124 for (rp=reserved; *rp; rp=next) {
1125 next = strchr(rp, '.') + 1;
1126 if (strncmp(name+3, rp, next-rp) == 0)
1127 break;
1128 }
1129 if (*rp) {
1130 if (ldd_mode) {
1131 /* Track which names have been resolved
1132 * and only report each one once. */
1133 static unsigned reported;
1134 unsigned mask = 1U<<(rp-reserved);
1135 if (!(reported & mask)) {
1136 reported |= mask;
1137 dprintf(1, "\t%s => %s (%p)\n",
1138 name, ldso.name,
1139 ldso.base);
1140 }
1141 }
1142 is_self = 1;
1143 }
1144 }
1145 if (!strcmp(name, ldso.name)) is_self = 1;
1146 if (is_self) {
1147 if (!ldso.prev) {
1148 tail->next = &ldso;
1149 ldso.prev = tail;
1150 tail = &ldso;
1151 }
1152 return &ldso;
1153 }
1154 if (strchr(name, '/')) {
1155 pathname = name;
1156 fd = open(name, O_RDONLY|O_CLOEXEC);
1157 } else {
1158 /* Search for the name to see if it's already loaded */
1159 for (p=head->next; p; p=p->next) {
1160 if (p->shortname && !strcmp(p->shortname, name)) {
1161 return p;
1162 }
1163 }
1164 if (strlen(name) > NAME_MAX) return 0;
1165 fd = -1;
1166 if (env_path) fd = path_open_library(name, env_path, buf, sizeof buf);
1167 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1168 if (fixup_rpath(p, buf, sizeof buf) < 0)
1169 fd = -2; /* Inhibit further search. */
1170 if (p->rpath)
1171 fd = path_open_library(name, p->rpath, buf, sizeof buf);
1172 }
1173 if (fd == -1) {
1174 if (!sys_path) {
1175 char *prefix = 0;
1176 size_t prefix_len;
1177 if (ldso.name[0]=='/') {
1178 char *s, *t, *z;
1179 for (s=t=z=ldso.name; *s; s++)
1180 if (*s=='/') z=t, t=s;
1181 prefix_len = z-ldso.name;
1182 if (prefix_len < PATH_MAX)
1183 prefix = ldso.name;
1184 }
1185 if (!prefix) {
1186 prefix = "";
1187 prefix_len = 0;
1188 }
1189 char etc_ldso_path[prefix_len + 1
1190 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1191 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1192 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1193 (int)prefix_len, prefix);
1194 fd = open(etc_ldso_path, O_RDONLY|O_CLOEXEC);
1195 if (fd>=0) {
1196 size_t n = 0;
1197 if (!fstat(fd, &st)) n = st.st_size;
1198 if ((sys_path = malloc(n+1)))
1199 sys_path[n] = 0;
1200 if (!sys_path || read_loop(fd, sys_path, n)<0) {
1201 free(sys_path);
1202 sys_path = "";
1203 }
1204 close(fd);
1205 } else if (errno != ENOENT) {
1206 sys_path = "";
1207 }
1208 }
1209 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1210 fd = path_open_library(name, sys_path, buf, sizeof buf);
1211 }
1212 pathname = buf;
1213 }
1214 if (fd < 0) return 0;
1215 if (fstat(fd, &st) < 0) {
1216 close(fd);
1217 return 0;
1218 }
1219 for (p=head->next; p; p=p->next) {
1220 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1221 /* If this library was previously loaded with a
1222 * pathname but a search found the same inode,
1223 * setup its shortname so it can be found by name. */
1224 if (!p->shortname && pathname != name)
1225 p->shortname = strrchr(p->name, '/')+1;
1226 close(fd);
1227 return p;
1228 }
1229 }
1230 map = noload ? 0 : map_library(fd, &temp_dso);
1231 close(fd);
1232 if (!map) return 0;
1233
1234 /* Avoid the danger of getting two versions of libc mapped into the
1235 * same process when an absolute pathname was used. The symbols
1236 * checked are chosen to catch both musl and glibc, and to avoid
1237 * false positives from interposition-hack libraries. */
1238 decode_dyn(&temp_dso);
1239 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1240 find_sym(&temp_dso, "stdin", 1).sym) {
1241 unmap_library(&temp_dso);
1242 return load_library(STRINGIFY(LIBC_SONAME), needed_by);
1243 }
1244 /* Past this point, if we haven't reached runtime yet, ldso has
1245 * committed either to use the mapped library or to abort execution.
1246 * Unmapping is not possible, so we can safely reclaim gaps. */
1247 if (!runtime) reclaim_gaps(&temp_dso);
1248
1249 /* Allocate storage for the new DSO. When there is TLS, this
1250 * storage must include a reservation for all pre-existing
1251 * threads to obtain copies of both the new TLS, and an
1252 * extended DTV capable of storing an additional slot for
1253 * the newly-loaded DSO. */
1254 alloc_size = sizeof *p + strlen(pathname) + 1;
1255 if (runtime && temp_dso.tls.image) {
1256 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1257 + sizeof(void *) * (tls_cnt+3);
1258 n_th = libc.threads_minus_1 + 1;
1259 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1260 else alloc_size += n_th * per_th;
1261 }
1262 p = calloc(1, alloc_size);
1263 if (!p) {
1264 unmap_library(&temp_dso);
1265 return 0;
1266 }
1267 memcpy(p, &temp_dso, sizeof temp_dso);
1268 p->dev = st.st_dev;
1269 p->ino = st.st_ino;
1270 p->needed_by = needed_by;
1271 p->name = p->buf;
1272 p->runtime_loaded = runtime;
1273 strcpy(p->name, pathname);
1274 /* Add a shortname only if name arg was not an explicit pathname. */
1275 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1276 if (p->tls.image) {
1277 p->tls_id = ++tls_cnt;
1278 tls_align = MAXP2(tls_align, p->tls.align);
1279 #ifdef TLS_ABOVE_TP
1280 p->tls.offset = tls_offset + ( (p->tls.align-1) &
1281 (-tls_offset + (uintptr_t)p->tls.image) );
1282 tls_offset = p->tls.offset + p->tls.size;
1283 #else
1284 tls_offset += p->tls.size + p->tls.align - 1;
1285 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1286 & (p->tls.align-1);
1287 p->tls.offset = tls_offset;
1288 #endif
1289 p->new_dtv = (void *)(-sizeof(size_t) &
1290 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1291 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1292 if (tls_tail) tls_tail->next = &p->tls;
1293 else libc.tls_head = &p->tls;
1294 tls_tail = &p->tls;
1295 }
1296
1297 tail->next = p;
1298 p->prev = tail;
1299 tail = p;
1300
1301 if (DL_FDPIC) makefuncdescs(p);
1302
1303 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1304
1305 return p;
1306 }
1307
load_direct_deps(struct dso * p)1308 static void load_direct_deps(struct dso *p)
1309 {
1310 size_t i, cnt=0;
1311
1312 if (p->deps) return;
1313 /* For head, all preloads are direct pseudo-dependencies.
1314 * Count and include them now to avoid realloc later. */
1315 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1316 cnt++;
1317 for (i=0; p->dynv[i]; i+=2)
1318 if (p->dynv[i] == DT_NEEDED) cnt++;
1319 /* Use builtin buffer for apps with no external deps, to
1320 * preserve property of no runtime failure paths. */
1321 p->deps = (p==head && cnt<2) ? builtin_deps :
1322 calloc(cnt+1, sizeof *p->deps);
1323 if (!p->deps) {
1324 error("Error loading dependencies for %s", p->name);
1325 if (runtime) longjmp(*rtld_fail, 1);
1326 }
1327 cnt=0;
1328 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1329 p->deps[cnt++] = q;
1330 for (i=0; p->dynv[i]; i+=2) {
1331 if (p->dynv[i] != DT_NEEDED) continue;
1332 struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
1333 if (!dep) {
1334 error("Error loading shared library %s: %m (needed by %s)",
1335 p->strings + p->dynv[i+1], p->name);
1336 if (runtime) longjmp(*rtld_fail, 1);
1337 continue;
1338 }
1339 p->deps[cnt++] = dep;
1340 }
1341 p->deps[cnt] = 0;
1342 p->ndeps_direct = cnt;
1343 }
1344
load_deps(struct dso * p)1345 static void load_deps(struct dso *p)
1346 {
1347 if (p->deps) return;
1348 for (; p; p=p->next)
1349 load_direct_deps(p);
1350 }
1351
extend_bfs_deps(struct dso * p)1352 static void extend_bfs_deps(struct dso *p)
1353 {
1354 size_t i, j, cnt, ndeps_all;
1355 struct dso **tmp;
1356
1357 /* Can't use realloc if the original p->deps was allocated at
1358 * program entry and malloc has been replaced, or if it's
1359 * the builtin non-allocated trivial main program deps array. */
1360 int no_realloc = (__malloc_replaced && !p->runtime_loaded)
1361 || p->deps == builtin_deps;
1362
1363 if (p->bfs_built) return;
1364 ndeps_all = p->ndeps_direct;
1365
1366 /* Mark existing (direct) deps so they won't be duplicated. */
1367 for (i=0; p->deps[i]; i++)
1368 p->deps[i]->mark = 1;
1369
1370 /* For each dependency already in the list, copy its list of direct
1371 * dependencies to the list, excluding any items already in the
1372 * list. Note that the list this loop iterates over will grow during
1373 * the loop, but since duplicates are excluded, growth is bounded. */
1374 for (i=0; p->deps[i]; i++) {
1375 struct dso *dep = p->deps[i];
1376 for (j=cnt=0; j<dep->ndeps_direct; j++)
1377 if (!dep->deps[j]->mark) cnt++;
1378 tmp = no_realloc ?
1379 malloc(sizeof(*tmp) * (ndeps_all+cnt+1)) :
1380 realloc(p->deps, sizeof(*tmp) * (ndeps_all+cnt+1));
1381 if (!tmp) {
1382 error("Error recording dependencies for %s", p->name);
1383 if (runtime) longjmp(*rtld_fail, 1);
1384 continue;
1385 }
1386 if (no_realloc) {
1387 memcpy(tmp, p->deps, sizeof(*tmp) * (ndeps_all+1));
1388 no_realloc = 0;
1389 }
1390 p->deps = tmp;
1391 for (j=0; j<dep->ndeps_direct; j++) {
1392 if (dep->deps[j]->mark) continue;
1393 dep->deps[j]->mark = 1;
1394 p->deps[ndeps_all++] = dep->deps[j];
1395 }
1396 p->deps[ndeps_all] = 0;
1397 }
1398 p->bfs_built = 1;
1399 for (p=head; p; p=p->next)
1400 p->mark = 0;
1401 }
1402
load_preload(char * s)1403 static void load_preload(char *s)
1404 {
1405 int tmp;
1406 char *z;
1407 for (z=s; *z; s=z) {
1408 for ( ; *s && (isspace(*s) || *s==':'); s++);
1409 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1410 tmp = *z;
1411 *z = 0;
1412 load_library(s, 0);
1413 *z = tmp;
1414 }
1415 }
1416
add_syms(struct dso * p)1417 static void add_syms(struct dso *p)
1418 {
1419 if (!p->syms_next && syms_tail != p) {
1420 syms_tail->syms_next = p;
1421 syms_tail = p;
1422 }
1423 }
1424
revert_syms(struct dso * old_tail)1425 static void revert_syms(struct dso *old_tail)
1426 {
1427 struct dso *p, *next;
1428 /* Chop off the tail of the list of dsos that participate in
1429 * the global symbol table, reverting them to RTLD_LOCAL. */
1430 for (p=old_tail; p; p=next) {
1431 next = p->syms_next;
1432 p->syms_next = 0;
1433 }
1434 syms_tail = old_tail;
1435 }
1436
do_mips_relocs(struct dso * p,size_t * got)1437 static void do_mips_relocs(struct dso *p, size_t *got)
1438 {
1439 size_t i, j, rel[2];
1440 unsigned char *base = p->base;
1441 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1442 if (p==&ldso) {
1443 got += i;
1444 } else {
1445 while (i--) *got++ += (size_t)base;
1446 }
1447 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1448 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1449 Sym *sym = p->syms + j;
1450 rel[0] = (unsigned char *)got - base;
1451 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1452 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1453 do_relocs(p, rel, sizeof rel, 2);
1454 }
1455 }
1456
reloc_all(struct dso * p)1457 static void reloc_all(struct dso *p)
1458 {
1459 size_t dyn[DYN_CNT];
1460 for (; p; p=p->next) {
1461 if (p->relocated) continue;
1462 decode_vec(p->dynv, dyn, DYN_CNT);
1463 if (NEED_MIPS_GOT_RELOCS)
1464 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1465 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1466 2+(dyn[DT_PLTREL]==DT_RELA));
1467 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1468 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1469 if (!DL_FDPIC)
1470 do_relr_relocs(p, laddr(p, dyn[DT_RELR]), dyn[DT_RELRSZ]);
1471
1472 if (head != &ldso && p->relro_start != p->relro_end) {
1473 long ret = __syscall(SYS_mprotect, laddr(p, p->relro_start),
1474 p->relro_end-p->relro_start, PROT_READ);
1475 if (ret != 0 && ret != -ENOSYS) {
1476 error("Error relocating %s: RELRO protection failed: %m",
1477 p->name);
1478 if (runtime) longjmp(*rtld_fail, 1);
1479 }
1480 }
1481
1482 p->relocated = 1;
1483 }
1484 }
1485
kernel_mapped_dso(struct dso * p)1486 static void kernel_mapped_dso(struct dso *p)
1487 {
1488 size_t min_addr = -1, max_addr = 0, cnt;
1489 Phdr *ph = p->phdr;
1490 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1491 if (ph->p_type == PT_DYNAMIC) {
1492 p->dynv = laddr(p, ph->p_vaddr);
1493 } else if (ph->p_type == PT_GNU_RELRO) {
1494 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1495 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1496 } else if (ph->p_type == PT_GNU_STACK) {
1497 if (!runtime && ph->p_memsz > __default_stacksize) {
1498 __default_stacksize =
1499 ph->p_memsz < DEFAULT_STACK_MAX ?
1500 ph->p_memsz : DEFAULT_STACK_MAX;
1501 }
1502 }
1503 if (ph->p_type != PT_LOAD) continue;
1504 if (ph->p_vaddr < min_addr)
1505 min_addr = ph->p_vaddr;
1506 if (ph->p_vaddr+ph->p_memsz > max_addr)
1507 max_addr = ph->p_vaddr+ph->p_memsz;
1508 }
1509 min_addr &= -PAGE_SIZE;
1510 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1511 p->map = p->base + min_addr;
1512 p->map_len = max_addr - min_addr;
1513 p->kernel_mapped = 1;
1514 }
1515
__libc_exit_fini()1516 void __libc_exit_fini()
1517 {
1518 struct dso *p;
1519 size_t dyn[DYN_CNT];
1520 pthread_t self = __pthread_self();
1521
1522 /* Take both locks before setting shutting_down, so that
1523 * either lock is sufficient to read its value. The lock
1524 * order matches that in dlopen to avoid deadlock. */
1525 pthread_rwlock_wrlock(&lock);
1526 pthread_mutex_lock(&init_fini_lock);
1527 shutting_down = 1;
1528 pthread_rwlock_unlock(&lock);
1529 for (p=fini_head; p; p=p->fini_next) {
1530 while (p->ctor_visitor && p->ctor_visitor!=self)
1531 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1532 if (!p->constructed) continue;
1533 decode_vec(p->dynv, dyn, DYN_CNT);
1534 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1535 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1536 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1537 while (n--) ((void (*)(void))*--fn)();
1538 }
1539 #ifndef NO_LEGACY_INITFINI
1540 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1541 fpaddr(p, dyn[DT_FINI])();
1542 #endif
1543 }
1544 }
1545
__ldso_atfork(int who)1546 void __ldso_atfork(int who)
1547 {
1548 if (who<0) {
1549 pthread_rwlock_wrlock(&lock);
1550 pthread_mutex_lock(&init_fini_lock);
1551 } else {
1552 pthread_mutex_unlock(&init_fini_lock);
1553 pthread_rwlock_unlock(&lock);
1554 }
1555 }
1556
queue_ctors(struct dso * dso)1557 static struct dso **queue_ctors(struct dso *dso)
1558 {
1559 size_t cnt, qpos, spos, i;
1560 struct dso *p, **queue, **stack;
1561
1562 if (ldd_mode) return 0;
1563
1564 /* Bound on queue size is the total number of indirect deps.
1565 * If a bfs deps list was built, we can use it. Otherwise,
1566 * bound by the total number of DSOs, which is always safe and
1567 * is reasonable we use it (for main app at startup). */
1568 if (dso->bfs_built) {
1569 for (cnt=0; dso->deps[cnt]; cnt++)
1570 dso->deps[cnt]->mark = 0;
1571 cnt++; /* self, not included in deps */
1572 } else {
1573 for (cnt=0, p=head; p; cnt++, p=p->next)
1574 p->mark = 0;
1575 }
1576 cnt++; /* termination slot */
1577 if (dso==head && cnt <= countof(builtin_ctor_queue))
1578 queue = builtin_ctor_queue;
1579 else
1580 queue = calloc(cnt, sizeof *queue);
1581
1582 if (!queue) {
1583 error("Error allocating constructor queue: %m\n");
1584 if (runtime) longjmp(*rtld_fail, 1);
1585 return 0;
1586 }
1587
1588 /* Opposite ends of the allocated buffer serve as an output queue
1589 * and a working stack. Setup initial stack with just the argument
1590 * dso and initial queue empty... */
1591 stack = queue;
1592 qpos = 0;
1593 spos = cnt;
1594 stack[--spos] = dso;
1595 dso->next_dep = 0;
1596 dso->mark = 1;
1597
1598 /* Then perform pseudo-DFS sort, but ignoring circular deps. */
1599 while (spos<cnt) {
1600 p = stack[spos++];
1601 while (p->next_dep < p->ndeps_direct) {
1602 if (p->deps[p->next_dep]->mark) {
1603 p->next_dep++;
1604 } else {
1605 stack[--spos] = p;
1606 p = p->deps[p->next_dep];
1607 p->next_dep = 0;
1608 p->mark = 1;
1609 }
1610 }
1611 queue[qpos++] = p;
1612 }
1613 queue[qpos] = 0;
1614 for (i=0; i<qpos; i++) queue[i]->mark = 0;
1615 for (i=0; i<qpos; i++)
1616 if (queue[i]->ctor_visitor && queue[i]->ctor_visitor->tid < 0) {
1617 error("State of %s is inconsistent due to multithreaded fork\n",
1618 queue[i]->name);
1619 free(queue);
1620 if (runtime) longjmp(*rtld_fail, 1);
1621 }
1622
1623 return queue;
1624 }
1625
do_init_fini(struct dso ** queue)1626 static void do_init_fini(struct dso **queue)
1627 {
1628 struct dso *p;
1629 size_t dyn[DYN_CNT], i;
1630 pthread_t self = __pthread_self();
1631
1632 pthread_mutex_lock(&init_fini_lock);
1633 for (i=0; (p=queue[i]); i++) {
1634 while ((p->ctor_visitor && p->ctor_visitor!=self) || shutting_down)
1635 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1636 if (p->ctor_visitor || p->constructed)
1637 continue;
1638 p->ctor_visitor = self;
1639
1640 decode_vec(p->dynv, dyn, DYN_CNT);
1641 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1642 p->fini_next = fini_head;
1643 fini_head = p;
1644 }
1645
1646 pthread_mutex_unlock(&init_fini_lock);
1647
1648 #ifndef NO_LEGACY_INITFINI
1649 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1650 fpaddr(p, dyn[DT_INIT])();
1651 #endif
1652 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1653 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1654 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1655 while (n--) ((void (*)(void))*fn++)();
1656 }
1657
1658 pthread_mutex_lock(&init_fini_lock);
1659 p->ctor_visitor = 0;
1660 p->constructed = 1;
1661 pthread_cond_broadcast(&ctor_cond);
1662 }
1663 pthread_mutex_unlock(&init_fini_lock);
1664 }
1665
__libc_start_init(void)1666 void __libc_start_init(void)
1667 {
1668 do_init_fini(main_ctor_queue);
1669 if (!__malloc_replaced && main_ctor_queue != builtin_ctor_queue)
1670 free(main_ctor_queue);
1671 main_ctor_queue = 0;
1672 }
1673
dl_debug_state(void)1674 static void dl_debug_state(void)
1675 {
1676 if (exe_dl_debug_state)
1677 exe_dl_debug_state();
1678 }
1679
1680 weak_alias(dl_debug_state, _dl_debug_state);
1681
__init_tls(size_t * auxv)1682 void __init_tls(size_t *auxv)
1683 {
1684 }
1685
update_tls_size()1686 static void update_tls_size()
1687 {
1688 libc.tls_cnt = tls_cnt;
1689 libc.tls_align = tls_align;
1690 libc.tls_size = ALIGN(
1691 (1+tls_cnt) * sizeof(void *) +
1692 tls_offset +
1693 sizeof(struct pthread) +
1694 tls_align * 2,
1695 tls_align);
1696 }
1697
install_new_tls(void)1698 static void install_new_tls(void)
1699 {
1700 sigset_t set;
1701 pthread_t self = __pthread_self(), td;
1702 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1703 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1704 struct dso *p;
1705 size_t i, j;
1706 size_t old_cnt = self->dtv[0];
1707
1708 __block_app_sigs(&set);
1709 __tl_lock();
1710 /* Copy existing dtv contents from all existing threads. */
1711 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1712 memcpy(newdtv+i, td->dtv,
1713 (old_cnt+1)*sizeof(uintptr_t));
1714 newdtv[i][0] = tls_cnt;
1715 }
1716 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1717 for (p=head; ; p=p->next) {
1718 if (p->tls_id <= old_cnt) continue;
1719 unsigned char *mem = p->new_tls;
1720 for (j=0; j<i; j++) {
1721 unsigned char *new = mem;
1722 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1723 & (p->tls.align-1);
1724 memcpy(new, p->tls.image, p->tls.len);
1725 newdtv[j][p->tls_id] =
1726 (uintptr_t)new + DTP_OFFSET;
1727 mem += p->tls.size + p->tls.align;
1728 }
1729 if (p->tls_id == tls_cnt) break;
1730 }
1731
1732 /* Broadcast barrier to ensure contents of new dtv is visible
1733 * if the new dtv pointer is. The __membarrier function has a
1734 * fallback emulation using signals for kernels that lack the
1735 * feature at the syscall level. */
1736
1737 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1738
1739 /* Install new dtv for each thread. */
1740 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1741 td->dtv = newdtv[j];
1742 }
1743
1744 __tl_unlock();
1745 __restore_sigs(&set);
1746 }
1747
1748 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1749 * following stage 2 and stage 3 functions via primitive symbolic lookup
1750 * since it does not have access to their addresses to begin with. */
1751
1752 /* Stage 2 of the dynamic linker is called after relative relocations
1753 * have been processed. It can make function calls to static functions
1754 * and access string literals and static data, but cannot use extern
1755 * symbols. Its job is to perform symbolic relocations on the dynamic
1756 * linker itself, but some of the relocations performed may need to be
1757 * replaced later due to copy relocations in the main program. */
1758
__dls2(unsigned char * base,size_t * sp)1759 hidden void __dls2(unsigned char *base, size_t *sp)
1760 {
1761 size_t *auxv;
1762 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1763 auxv++;
1764 if (DL_FDPIC) {
1765 void *p1 = (void *)sp[-2];
1766 void *p2 = (void *)sp[-1];
1767 if (!p1) {
1768 size_t aux[AUX_CNT];
1769 decode_vec(auxv, aux, AUX_CNT);
1770 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1771 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1772 }
1773 app_loadmap = p2 ? p1 : 0;
1774 ldso.loadmap = p2 ? p2 : p1;
1775 ldso.base = laddr(&ldso, 0);
1776 } else {
1777 ldso.base = base;
1778 }
1779 Ehdr *ehdr = __ehdr_start ? (void *)__ehdr_start : (void *)ldso.base;
1780 ldso.name = ldso.shortname = STRINGIFY(LIBC_SONAME);
1781 ldso.phnum = ehdr->e_phnum;
1782 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1783 ldso.phentsize = ehdr->e_phentsize;
1784 ldso.elfmachine = ehdr->e_machine;
1785 ldso.elfclass = ehdr->e_ident[EI_CLASS];
1786 search_vec(auxv, &ldso_page_size, AT_PAGESZ);
1787 kernel_mapped_dso(&ldso);
1788 decode_dyn(&ldso);
1789
1790 if (DL_FDPIC) makefuncdescs(&ldso);
1791
1792 /* Prepare storage for to save clobbered REL addends so they
1793 * can be reused in stage 3. There should be very few. If
1794 * something goes wrong and there are a huge number, abort
1795 * instead of risking stack overflow. */
1796 size_t dyn[DYN_CNT];
1797 decode_vec(ldso.dynv, dyn, DYN_CNT);
1798 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1799 size_t rel_size = dyn[DT_RELSZ];
1800 size_t symbolic_rel_cnt = 0;
1801 apply_addends_to = rel;
1802 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1803 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1804 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1805 size_t addends[symbolic_rel_cnt+1];
1806 saved_addends = addends;
1807
1808 head = &ldso;
1809 reloc_all(&ldso);
1810
1811 ldso.relocated = 0;
1812
1813 /* Call dynamic linker stage-2b, __dls2b, looking it up
1814 * symbolically as a barrier against moving the address
1815 * load across the above relocation processing. */
1816 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1817 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp, auxv);
1818 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp, auxv);
1819 }
1820
1821 /* Stage 2b sets up a valid thread pointer, which requires relocations
1822 * completed in stage 2, and on which stage 3 is permitted to depend.
1823 * This is done as a separate stage, with symbolic lookup as a barrier,
1824 * so that loads of the thread pointer and &errno can be pure/const and
1825 * thereby hoistable. */
1826
__dls2b(size_t * sp,size_t * auxv)1827 void __dls2b(size_t *sp, size_t *auxv)
1828 {
1829 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1830 * use during dynamic linking. If possible it will also serve as the
1831 * thread pointer at runtime. */
1832 search_vec(auxv, &__hwcap, AT_HWCAP);
1833 libc.auxv = auxv;
1834 libc.tls_size = sizeof builtin_tls;
1835 libc.tls_align = tls_align;
1836 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1837 a_crash();
1838 }
1839
1840 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1841 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp, auxv);
1842 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp, auxv);
1843 }
1844
1845 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1846 * fully functional. Its job is to load (if not already loaded) and
1847 * process dependencies and relocations for the main application and
1848 * transfer control to its entry point. */
1849
__dls3(size_t * sp,size_t * auxv)1850 void __dls3(size_t *sp, size_t *auxv)
1851 {
1852 static struct dso app, vdso;
1853 size_t aux[AUX_CNT];
1854 size_t i;
1855 char *env_preload=0;
1856 char *replace_argv0=0;
1857 size_t vdso_base;
1858 int argc = *sp;
1859 char **argv = (void *)(sp+1);
1860 char **argv_orig = argv;
1861 char **envp = argv+argc+1;
1862
1863 /* Find aux vector just past environ[] and use it to initialize
1864 * global data that may be needed before we can make syscalls. */
1865 __environ = envp;
1866 decode_vec(auxv, aux, AUX_CNT);
1867 search_vec(auxv, &__sysinfo, AT_SYSINFO);
1868 __pthread_self()->sysinfo = __sysinfo;
1869 libc.page_size = aux[AT_PAGESZ];
1870 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1871 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1872
1873 /* Only trust user/env if kernel says we're not suid/sgid */
1874 if (!libc.secure) {
1875 env_path = getenv("LD_LIBRARY_PATH");
1876 env_preload = getenv("LD_PRELOAD");
1877 }
1878
1879 /* Activate error handler function */
1880 error = error_impl;
1881
1882 /* If the main program was already loaded by the kernel,
1883 * AT_PHDR will point to some location other than the dynamic
1884 * linker's program headers. */
1885 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1886 size_t interp_off = 0;
1887 size_t tls_image = 0;
1888 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1889 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1890 app.phnum = aux[AT_PHNUM];
1891 app.phentsize = aux[AT_PHENT];
1892 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1893 if (phdr->p_type == PT_PHDR)
1894 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1895 else if (phdr->p_type == PT_INTERP)
1896 interp_off = (size_t)phdr->p_vaddr;
1897 else if (phdr->p_type == PT_TLS) {
1898 tls_image = phdr->p_vaddr;
1899 app.tls.len = phdr->p_filesz;
1900 app.tls.size = phdr->p_memsz;
1901 app.tls.align = phdr->p_align;
1902 }
1903 }
1904 if (DL_FDPIC) app.loadmap = app_loadmap;
1905 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1906 if (interp_off) ldso.name = laddr(&app, interp_off);
1907 if ((aux[0] & (1UL<<AT_EXECFN))
1908 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1909 app.name = (char *)aux[AT_EXECFN];
1910 else
1911 app.name = argv[0];
1912 kernel_mapped_dso(&app);
1913 } else {
1914 int fd;
1915 char *ldname = argv[0];
1916 size_t l = strlen(ldname);
1917 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1918 argv++;
1919 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1920 char *opt = argv[0]+2;
1921 *argv++ = (void *)-1;
1922 if (!*opt) {
1923 break;
1924 } else if (!memcmp(opt, "list", 5)) {
1925 ldd_mode = 1;
1926 } else if (!memcmp(opt, "library-path", 12)) {
1927 if (opt[12]=='=') env_path = opt+13;
1928 else if (opt[12]) *argv = 0;
1929 else if (*argv) env_path = *argv++;
1930 } else if (!memcmp(opt, "preload", 7)) {
1931 if (opt[7]=='=') env_preload = opt+8;
1932 else if (opt[7]) *argv = 0;
1933 else if (*argv) env_preload = *argv++;
1934 } else if (!memcmp(opt, "argv0", 5)) {
1935 if (opt[5]=='=') replace_argv0 = opt+6;
1936 else if (opt[5]) *argv = 0;
1937 else if (*argv) replace_argv0 = *argv++;
1938 } else {
1939 argv[0] = 0;
1940 }
1941 }
1942 argv[-1] = (void *)(argc - (argv-argv_orig));
1943 if (!argv[0]) {
1944 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1945 "Version %s\n"
1946 "Dynamic Program Loader\n"
1947 "Usage: %s [options] [--] pathname%s\n",
1948 __libc_version, ldname,
1949 ldd_mode ? "" : " [args]");
1950 _exit(1);
1951 }
1952 fd = open(argv[0], O_RDONLY);
1953 if (fd < 0) {
1954 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1955 _exit(1);
1956 }
1957 Ehdr *ehdr = map_library(fd, &app);
1958 if (!ehdr) {
1959 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1960 _exit(1);
1961 }
1962 close(fd);
1963 ldso.name = ldname;
1964 app.name = argv[0];
1965 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1966 /* Find the name that would have been used for the dynamic
1967 * linker had ldd not taken its place. */
1968 if (ldd_mode) {
1969 for (i=0; i<app.phnum; i++) {
1970 if (app.phdr[i].p_type == PT_INTERP)
1971 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1972 }
1973 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1974 }
1975 }
1976 if (app.tls.size) {
1977 libc.tls_head = tls_tail = &app.tls;
1978 app.tls_id = tls_cnt = 1;
1979 #ifdef TLS_ABOVE_TP
1980 app.tls.offset = GAP_ABOVE_TP;
1981 app.tls.offset += (-GAP_ABOVE_TP + (uintptr_t)app.tls.image)
1982 & (app.tls.align-1);
1983 tls_offset = app.tls.offset + app.tls.size;
1984 #else
1985 tls_offset = app.tls.offset = app.tls.size
1986 + ( -((uintptr_t)app.tls.image + app.tls.size)
1987 & (app.tls.align-1) );
1988 #endif
1989 tls_align = MAXP2(tls_align, app.tls.align);
1990 }
1991 decode_dyn(&app);
1992 if (DL_FDPIC) {
1993 makefuncdescs(&app);
1994 if (!app.loadmap) {
1995 app.loadmap = (void *)&app_dummy_loadmap;
1996 app.loadmap->nsegs = 1;
1997 app.loadmap->segs[0].addr = (size_t)app.map;
1998 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1999 - (size_t)app.base;
2000 app.loadmap->segs[0].p_memsz = app.map_len;
2001 }
2002 argv[-3] = (void *)app.loadmap;
2003 }
2004
2005 /* Initial dso chain consists only of the app. */
2006 head = tail = syms_tail = &app;
2007
2008 /* Donate unused parts of app and library mapping to malloc */
2009 reclaim_gaps(&app);
2010 reclaim_gaps(&ldso);
2011
2012 /* Load preload/needed libraries, add symbols to global namespace. */
2013 ldso.deps = (struct dso **)no_deps;
2014 if (env_preload) load_preload(env_preload);
2015 load_deps(&app);
2016 for (struct dso *p=head; p; p=p->next)
2017 add_syms(p);
2018
2019 /* Attach to vdso, if provided by the kernel, last so that it does
2020 * not become part of the global namespace. */
2021 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
2022 Ehdr *ehdr = (void *)vdso_base;
2023 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
2024 vdso.phnum = ehdr->e_phnum;
2025 vdso.phentsize = ehdr->e_phentsize;
2026 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
2027 if (phdr->p_type == PT_DYNAMIC)
2028 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
2029 if (phdr->p_type == PT_LOAD)
2030 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
2031 }
2032 vdso.name = "";
2033 vdso.shortname = "linux-gate.so.1";
2034 vdso.relocated = 1;
2035 vdso.deps = (struct dso **)no_deps;
2036 decode_dyn(&vdso);
2037 vdso.prev = tail;
2038 tail->next = &vdso;
2039 tail = &vdso;
2040 }
2041
2042 for (i=0; app.dynv[i]; i+=2) {
2043 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
2044 app.dynv[i+1] = (size_t)&debug;
2045 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
2046 size_t *ptr = (size_t *) app.dynv[i+1];
2047 *ptr = (size_t)&debug;
2048 }
2049 if (app.dynv[i]==DT_DEBUG_INDIRECT_REL) {
2050 size_t *ptr = (size_t *)((size_t)&app.dynv[i] + app.dynv[i+1]);
2051 *ptr = (size_t)&debug;
2052 }
2053 }
2054
2055 /* This must be done before final relocations, since it calls
2056 * malloc, which may be provided by the application. Calling any
2057 * application code prior to the jump to its entry point is not
2058 * valid in our model and does not work with FDPIC, where there
2059 * are additional relocation-like fixups that only the entry point
2060 * code can see to perform. */
2061 main_ctor_queue = queue_ctors(&app);
2062
2063 /* Initial TLS must also be allocated before final relocations
2064 * might result in calloc being a call to application code. */
2065 update_tls_size();
2066 void *initial_tls = builtin_tls;
2067 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
2068 initial_tls = calloc(libc.tls_size, 1);
2069 if (!initial_tls) {
2070 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
2071 argv[0], libc.tls_size);
2072 _exit(127);
2073 }
2074 }
2075 static_tls_cnt = tls_cnt;
2076
2077 /* The main program must be relocated LAST since it may contain
2078 * copy relocations which depend on libraries' relocations. */
2079 reloc_all(app.next);
2080 reloc_all(&app);
2081
2082 /* Actual copying to new TLS needs to happen after relocations,
2083 * since the TLS images might have contained relocated addresses. */
2084 if (initial_tls != builtin_tls) {
2085 if (__init_tp(__copy_tls(initial_tls)) < 0) {
2086 a_crash();
2087 }
2088 } else {
2089 size_t tmp_tls_size = libc.tls_size;
2090 pthread_t self = __pthread_self();
2091 /* Temporarily set the tls size to the full size of
2092 * builtin_tls so that __copy_tls will use the same layout
2093 * as it did for before. Then check, just to be safe. */
2094 libc.tls_size = sizeof builtin_tls;
2095 if (__copy_tls((void*)builtin_tls) != self) a_crash();
2096 libc.tls_size = tmp_tls_size;
2097 }
2098
2099 if (ldso_fail) _exit(127);
2100 if (ldd_mode) _exit(0);
2101
2102 /* Determine if malloc was interposed by a replacement implementation
2103 * so that calloc and the memalign family can harden against the
2104 * possibility of incomplete replacement. */
2105 if (find_sym(head, "malloc", 1).dso != &ldso)
2106 __malloc_replaced = 1;
2107 if (find_sym(head, "aligned_alloc", 1).dso != &ldso)
2108 __aligned_alloc_replaced = 1;
2109
2110 /* Determine if another DSO is providing the _dl_debug_state symbol
2111 * and forward calls to it. */
2112 struct symdef debug_sym = find_sym(head, "_dl_debug_state", 1);
2113 if (debug_sym.dso != &ldso)
2114 exe_dl_debug_state = (void (*)(void))laddr(debug_sym.dso, debug_sym.sym->st_value);
2115
2116 /* Switch to runtime mode: any further failures in the dynamic
2117 * linker are a reportable failure rather than a fatal startup
2118 * error. */
2119 runtime = 1;
2120
2121 debug.ver = 1;
2122 debug.bp = dl_debug_state;
2123 debug.head = head;
2124 debug.base = ldso.base;
2125 debug.state = RT_CONSISTENT;
2126 _dl_debug_state();
2127
2128 if (replace_argv0) argv[0] = replace_argv0;
2129
2130 errno = 0;
2131
2132 CRTJMP((void *)aux[AT_ENTRY], argv-1);
2133 for(;;);
2134 }
2135
prepare_lazy(struct dso * p)2136 static void prepare_lazy(struct dso *p)
2137 {
2138 size_t dyn[DYN_CNT], n, flags1=0;
2139 decode_vec(p->dynv, dyn, DYN_CNT);
2140 search_vec(p->dynv, &flags1, DT_FLAGS_1);
2141 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
2142 return;
2143 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
2144 if (NEED_MIPS_GOT_RELOCS) {
2145 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
2146 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
2147 n += i-j;
2148 }
2149 p->lazy = calloc(n, 3*sizeof(size_t));
2150 if (!p->lazy) {
2151 error("Error preparing lazy relocation for %s: %m", p->name);
2152 longjmp(*rtld_fail, 1);
2153 }
2154 p->lazy_next = lazy_head;
2155 lazy_head = p;
2156 }
2157
dlopen(const char * file,int mode)2158 void *dlopen(const char *file, int mode)
2159 {
2160 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
2161 struct tls_module *orig_tls_tail;
2162 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
2163 size_t i;
2164 int cs;
2165 jmp_buf jb;
2166 struct dso **volatile ctor_queue = 0;
2167
2168 if (!file) return head;
2169
2170 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
2171 pthread_rwlock_wrlock(&lock);
2172 __inhibit_ptc();
2173
2174 debug.state = RT_ADD;
2175 _dl_debug_state();
2176
2177 p = 0;
2178 if (shutting_down) {
2179 error("Cannot dlopen while program is exiting.");
2180 goto end;
2181 }
2182 orig_tls_tail = tls_tail;
2183 orig_tls_cnt = tls_cnt;
2184 orig_tls_offset = tls_offset;
2185 orig_tls_align = tls_align;
2186 orig_lazy_head = lazy_head;
2187 orig_syms_tail = syms_tail;
2188 orig_tail = tail;
2189 noload = mode & RTLD_NOLOAD;
2190
2191 rtld_fail = &jb;
2192 if (setjmp(*rtld_fail)) {
2193 /* Clean up anything new that was (partially) loaded */
2194 revert_syms(orig_syms_tail);
2195 for (p=orig_tail->next; p; p=next) {
2196 next = p->next;
2197 while (p->td_index) {
2198 void *tmp = p->td_index->next;
2199 free(p->td_index);
2200 p->td_index = tmp;
2201 }
2202 free(p->funcdescs);
2203 if (p->rpath != p->rpath_orig)
2204 free(p->rpath);
2205 free(p->deps);
2206 unmap_library(p);
2207 free(p);
2208 }
2209 free(ctor_queue);
2210 ctor_queue = 0;
2211 if (!orig_tls_tail) libc.tls_head = 0;
2212 tls_tail = orig_tls_tail;
2213 if (tls_tail) tls_tail->next = 0;
2214 tls_cnt = orig_tls_cnt;
2215 tls_offset = orig_tls_offset;
2216 tls_align = orig_tls_align;
2217 lazy_head = orig_lazy_head;
2218 tail = orig_tail;
2219 tail->next = 0;
2220 p = 0;
2221 goto end;
2222 } else p = load_library(file, head);
2223
2224 if (!p) {
2225 error(noload ?
2226 "Library %s is not already loaded" :
2227 "Error loading shared library %s: %m",
2228 file);
2229 goto end;
2230 }
2231
2232 /* First load handling */
2233 load_deps(p);
2234 extend_bfs_deps(p);
2235 pthread_mutex_lock(&init_fini_lock);
2236 int constructed = p->constructed;
2237 pthread_mutex_unlock(&init_fini_lock);
2238 if (!constructed) ctor_queue = queue_ctors(p);
2239 if (!p->relocated && (mode & RTLD_LAZY)) {
2240 prepare_lazy(p);
2241 for (i=0; p->deps[i]; i++)
2242 if (!p->deps[i]->relocated)
2243 prepare_lazy(p->deps[i]);
2244 }
2245 if (!p->relocated || (mode & RTLD_GLOBAL)) {
2246 /* Make new symbols global, at least temporarily, so we can do
2247 * relocations. If not RTLD_GLOBAL, this is reverted below. */
2248 add_syms(p);
2249 for (i=0; p->deps[i]; i++)
2250 add_syms(p->deps[i]);
2251 }
2252 if (!p->relocated) {
2253 reloc_all(p);
2254 }
2255
2256 /* If RTLD_GLOBAL was not specified, undo any new additions
2257 * to the global symbol table. This is a nop if the library was
2258 * previously loaded and already global. */
2259 if (!(mode & RTLD_GLOBAL))
2260 revert_syms(orig_syms_tail);
2261
2262 /* Processing of deferred lazy relocations must not happen until
2263 * the new libraries are committed; otherwise we could end up with
2264 * relocations resolved to symbol definitions that get removed. */
2265 redo_lazy_relocs();
2266
2267 update_tls_size();
2268 if (tls_cnt != orig_tls_cnt)
2269 install_new_tls();
2270 orig_tail = tail;
2271 end:
2272 debug.state = RT_CONSISTENT;
2273 _dl_debug_state();
2274 __release_ptc();
2275 if (p) gencnt++;
2276 pthread_rwlock_unlock(&lock);
2277 if (ctor_queue) {
2278 do_init_fini(ctor_queue);
2279 free(ctor_queue);
2280 }
2281 pthread_setcancelstate(cs, 0);
2282 return p;
2283 }
2284
__dl_invalid_handle(void * h)2285 hidden int __dl_invalid_handle(void *h)
2286 {
2287 struct dso *p;
2288 for (p=head; p; p=p->next) if (h==p) return 0;
2289 error("Invalid library handle %p", (void *)h);
2290 return 1;
2291 }
2292
addr2dso(size_t a)2293 static void *addr2dso(size_t a)
2294 {
2295 struct dso *p;
2296 size_t i;
2297 if (DL_FDPIC) for (p=head; p; p=p->next) {
2298 i = count_syms(p);
2299 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
2300 return p;
2301 }
2302 for (p=head; p; p=p->next) {
2303 if (DL_FDPIC && p->loadmap) {
2304 for (i=0; i<p->loadmap->nsegs; i++) {
2305 if (a-p->loadmap->segs[i].p_vaddr
2306 < p->loadmap->segs[i].p_memsz)
2307 return p;
2308 }
2309 } else {
2310 Phdr *ph = p->phdr;
2311 size_t phcnt = p->phnum;
2312 size_t entsz = p->phentsize;
2313 size_t base = (size_t)p->base;
2314 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
2315 if (ph->p_type != PT_LOAD) continue;
2316 if (a-base-ph->p_vaddr < ph->p_memsz)
2317 return p;
2318 }
2319 if (a-(size_t)p->map < p->map_len)
2320 return 0;
2321 }
2322 }
2323 return 0;
2324 }
2325
do_dlsym(struct dso * p,const char * s,void * ra)2326 static void *do_dlsym(struct dso *p, const char *s, void *ra)
2327 {
2328 int use_deps = 0;
2329 if (p == head || p == RTLD_DEFAULT) {
2330 p = head;
2331 } else if (p == RTLD_NEXT) {
2332 p = addr2dso((size_t)ra);
2333 if (!p) p=head;
2334 p = p->next;
2335 } else if (__dl_invalid_handle(p)) {
2336 return 0;
2337 } else
2338 use_deps = 1;
2339 struct symdef def = find_sym2(p, s, 0, use_deps);
2340 if (!def.sym) {
2341 error("Symbol not found: %s", s);
2342 return 0;
2343 }
2344 if ((def.sym->st_info&0xf) == STT_TLS)
2345 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
2346 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
2347 return def.dso->funcdescs + (def.sym - def.dso->syms);
2348 return laddr(def.dso, def.sym->st_value);
2349 }
2350
dladdr(const void * addr_arg,Dl_info * info)2351 int dladdr(const void *addr_arg, Dl_info *info)
2352 {
2353 size_t addr = (size_t)addr_arg;
2354 struct dso *p;
2355 Sym *sym, *bestsym;
2356 uint32_t nsym;
2357 char *strings;
2358 size_t best = 0;
2359 size_t besterr = -1;
2360
2361 pthread_rwlock_rdlock(&lock);
2362 p = addr2dso(addr);
2363 pthread_rwlock_unlock(&lock);
2364
2365 if (!p) return 0;
2366
2367 sym = p->syms;
2368 strings = p->strings;
2369 nsym = count_syms(p);
2370
2371 if (DL_FDPIC) {
2372 size_t idx = (addr-(size_t)p->funcdescs)
2373 / sizeof(*p->funcdescs);
2374 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2375 best = (size_t)(p->funcdescs + idx);
2376 bestsym = sym + idx;
2377 besterr = 0;
2378 }
2379 }
2380
2381 if (!best) for (; nsym; nsym--, sym++) {
2382 if (sym->st_value
2383 && (1<<(sym->st_info&0xf) & OK_TYPES)
2384 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2385 size_t symaddr = (size_t)laddr(p, sym->st_value);
2386 if (symaddr > addr || symaddr <= best)
2387 continue;
2388 best = symaddr;
2389 bestsym = sym;
2390 besterr = addr - symaddr;
2391 if (addr == symaddr)
2392 break;
2393 }
2394 }
2395
2396 if (best && besterr > bestsym->st_size-1) {
2397 best = 0;
2398 bestsym = 0;
2399 }
2400
2401 info->dli_fname = p->name;
2402 info->dli_fbase = p->map;
2403
2404 if (!best) {
2405 info->dli_sname = 0;
2406 info->dli_saddr = 0;
2407 return 1;
2408 }
2409
2410 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2411 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2412 info->dli_sname = strings + bestsym->st_name;
2413 info->dli_saddr = (void *)best;
2414
2415 return 1;
2416 }
2417
__dlsym(void * restrict p,const char * restrict s,void * restrict ra)2418 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2419 {
2420 void *res;
2421 pthread_rwlock_rdlock(&lock);
2422 res = do_dlsym(p, s, ra);
2423 pthread_rwlock_unlock(&lock);
2424 return res;
2425 }
2426
__dlsym_redir_time64(void * restrict p,const char * restrict s,void * restrict ra)2427 hidden void *__dlsym_redir_time64(void *restrict p, const char *restrict s, void *restrict ra)
2428 {
2429 #if _REDIR_TIME64
2430 const char *suffix, *suffix2 = "";
2431 char redir[36];
2432
2433 /* Map the symbol name to a time64 version of itself according to the
2434 * pattern used for naming the redirected time64 symbols. */
2435 size_t l = strnlen(s, sizeof redir);
2436 if (l<4 || l==sizeof redir) goto no_redir;
2437 if (s[l-2]=='_' && s[l-1]=='r') {
2438 l -= 2;
2439 suffix2 = s+l;
2440 }
2441 if (l<4) goto no_redir;
2442 if (!strcmp(s+l-4, "time")) suffix = "64";
2443 else suffix = "_time64";
2444
2445 /* Use the presence of the remapped symbol name in libc to determine
2446 * whether it's one that requires time64 redirection; replace if so. */
2447 snprintf(redir, sizeof redir, "__%.*s%s%s", (int)l, s, suffix, suffix2);
2448 if (find_sym(&ldso, redir, 1).sym) s = redir;
2449 no_redir:
2450 #endif
2451 return __dlsym(p, s, ra);
2452 }
2453
dl_iterate_phdr(int (* callback)(struct dl_phdr_info * info,size_t size,void * data),void * data)2454 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2455 {
2456 struct dso *current;
2457 struct dl_phdr_info info;
2458 int ret = 0;
2459 for(current = head; current;) {
2460 info.dlpi_addr = (uintptr_t)current->base;
2461 info.dlpi_name = current->name;
2462 info.dlpi_phdr = current->phdr;
2463 info.dlpi_phnum = current->phnum;
2464 info.dlpi_adds = gencnt;
2465 info.dlpi_subs = 0;
2466 info.dlpi_tls_modid = current->tls_id;
2467 info.dlpi_tls_data = !current->tls_id ? 0 :
2468 __tls_get_addr((tls_mod_off_t[]){current->tls_id,0});
2469
2470 ret = (callback)(&info, sizeof (info), data);
2471
2472 if (ret != 0) break;
2473
2474 pthread_rwlock_rdlock(&lock);
2475 current = current->next;
2476 pthread_rwlock_unlock(&lock);
2477 }
2478 return ret;
2479 }
2480
error_impl(const char * fmt,...)2481 static void error_impl(const char *fmt, ...)
2482 {
2483 va_list ap;
2484 va_start(ap, fmt);
2485 if (!runtime) {
2486 vdprintf(2, fmt, ap);
2487 dprintf(2, "\n");
2488 ldso_fail = 1;
2489 va_end(ap);
2490 return;
2491 }
2492 __dl_vseterr(fmt, ap);
2493 va_end(ap);
2494 }
2495
error_noop(const char * fmt,...)2496 static void error_noop(const char *fmt, ...)
2497 {
2498 }
2499