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