20 #include "pthread_impl.h"
24 static char errbuf[128];
28 #if ULONG_MAX == 0xffffffff
29 typedef Elf32_Ehdr Ehdr;
30 typedef Elf32_Phdr Phdr;
31 typedef Elf32_Sym Sym;
32 #define R_TYPE(x) ((x)&255)
33 #define R_SYM(x) ((x)>>8)
35 typedef Elf64_Ehdr Ehdr;
36 typedef Elf64_Phdr Phdr;
37 typedef Elf64_Sym Sym;
38 #define R_TYPE(x) ((x)&0xffffffff)
39 #define R_SYM(x) ((x)>>32)
42 #define MAXP2(a,b) (-(-(a)&-(b)))
43 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
55 struct td_index *next;
62 struct dso *next, *prev;
81 struct dso **deps, *needed_by;
82 char *rpath_orig, *rpath;
84 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
85 size_t relro_start, relro_end;
87 unsigned char *new_tls;
88 int new_dtv_idx, new_tls_idx;
89 struct td_index *td_index;
90 struct dso *fini_next;
110 REL_TLS, /* everything past here is TLS */
120 int __init_tp(void *);
121 void __init_libc(char **, char *);
123 const char *__libc_get_version(void);
125 static struct dso *head, *tail, *ldso, *fini_head;
126 static char *env_path, *sys_path;
127 static unsigned long long gencnt;
130 static int ldso_fail;
132 static jmp_buf *rtld_fail;
133 static pthread_rwlock_t lock;
134 static struct debug debug;
135 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
136 static size_t static_tls_cnt;
137 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
138 static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)];
140 struct debug *_dl_debug_addr = &debug;
145 static void decode_vec(size_t *v, size_t *a, size_t cnt)
147 memset(a, 0, cnt*sizeof(size_t));
148 for (; v[0]; v+=2) if (v[0]<cnt) {
154 static int search_vec(size_t *v, size_t *r, size_t key)
156 for (; v[0]!=key; v+=2)
162 static void error(const char *fmt, ...)
166 vsnprintf(errbuf, sizeof errbuf, fmt, ap);
168 if (runtime) longjmp(*rtld_fail, 1);
169 dprintf(2, "%s\n", errbuf);
173 static uint32_t sysv_hash(const char *s0)
175 const unsigned char *s = (void *)s0;
181 return h & 0xfffffff;
184 static uint32_t gnu_hash(const char *s0)
186 const unsigned char *s = (void *)s0;
187 uint_fast32_t h = 5381;
193 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
196 Sym *syms = dso->syms;
197 uint32_t *hashtab = dso->hashtab;
198 char *strings = dso->strings;
199 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
200 if ((!dso->versym || dso->versym[i] >= 0)
201 && (!strcmp(s, strings+syms[i].st_name)))
207 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
209 Sym *syms = dso->syms;
210 char *strings = dso->strings;
211 uint32_t *hashtab = dso->ghashtab;
212 uint32_t nbuckets = hashtab[0];
213 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
216 uint32_t i = buckets[h1 % nbuckets];
220 hashval = buckets + nbuckets + (i - hashtab[1]);
222 for (h1 |= 1; ; i++) {
224 if ((!dso->versym || dso->versym[i] >= 0)
225 && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
233 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
234 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
236 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
238 uint32_t h = 0, gh = 0;
239 struct symdef def = {0};
240 for (; dso; dso=dso->next) {
242 if (!dso->global) continue;
244 if (!gh) gh = gnu_hash(s);
245 sym = gnu_lookup(s, gh, dso);
247 if (!h) h = sysv_hash(s);
248 sym = sysv_lookup(s, h, dso);
252 if (need_def || (sym->st_info&0xf) == STT_TLS)
255 if ((sym->st_info&0xf) != STT_TLS)
257 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
258 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
260 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
263 if (sym->st_info>>4 == STB_GLOBAL) break;
268 #define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT)
270 ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
272 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
274 unsigned char *base = dso->base;
275 Sym *syms = dso->syms;
276 char *strings = dso->strings;
288 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
289 astype = R_TYPE(rel[1]);
290 if (!astype) continue;
291 type = remap_rel(astype);
293 error(errbuf, sizeof errbuf,
294 "Error relocating %s: unsupported relocation type %d",
298 sym_index = R_SYM(rel[1]);
299 reloc_addr = (void *)(base + rel[0]);
301 sym = syms + sym_index;
302 name = strings + sym->st_name;
303 ctx = type==REL_COPY ? head->next : head;
304 def = find_sym(ctx, name, type==REL_PLT);
305 if (!def.sym && (sym->st_shndx != SHN_UNDEF
306 || sym->st_info>>4 != STB_WEAK)) {
307 error(errbuf, sizeof errbuf,
308 "Error relocating %s: %s: symbol not found",
318 addend = stride>2 ? rel[2]
319 : (1<<type & NO_INLINE_ADDEND) ? 0
322 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
323 tls_val = def.sym ? def.sym->st_value : 0;
327 addend -= (size_t)reloc_addr;
331 *reloc_addr = sym_val + addend;
334 *reloc_addr = (size_t)base + addend;
337 if (sym) *reloc_addr = sym_val + addend;
338 else *reloc_addr = (size_t)base + addend;
341 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
344 *(uint32_t *)reloc_addr = sym_val + addend
345 - (size_t)reloc_addr;
348 *reloc_addr = def.dso->tls_id;
351 *reloc_addr = tls_val + addend;
355 *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
359 *reloc_addr = tls_val - def.dso->tls_offset + addend;
362 *reloc_addr = def.dso->tls_offset - tls_val + addend;
366 if (stride<3) addend = reloc_addr[1];
367 if (runtime && def.dso->tls_id >= static_tls_cnt) {
368 struct td_index *new = malloc(sizeof *new);
369 if (!new) error(errbuf, sizeof errbuf,
370 "Error relocating %s: cannot allocate TLSDESC for %s",
371 dso->name, sym ? name : "(local)" );
372 new->next = dso->td_index;
374 new->args[0] = def.dso->tls_id;
375 new->args[1] = tls_val + addend;
376 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
377 reloc_addr[1] = (size_t)new;
379 reloc_addr[0] = (size_t)__tlsdesc_static;
381 reloc_addr[1] = tls_val + def.dso->tls_offset
384 reloc_addr[1] = tls_val - def.dso->tls_offset
393 /* A huge hack: to make up for the wastefulness of shared libraries
394 * needing at least a page of dirty memory even if they have no global
395 * data, we reclaim the gaps at the beginning and end of writable maps
396 * and "donate" them to the heap by setting up minimal malloc
397 * structures and then freeing them. */
399 static void reclaim(struct dso *dso, size_t start, size_t end)
402 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
403 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
404 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
405 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
406 if (start>end || end-start < 4*sizeof(size_t)) return;
407 a = (size_t *)(dso->base + start);
408 z = (size_t *)(dso->base + end);
410 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
415 static void reclaim_gaps(struct dso *dso)
417 Phdr *ph = dso->phdr;
418 size_t phcnt = dso->phnum;
420 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
421 if (ph->p_type!=PT_LOAD) continue;
422 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
423 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
424 reclaim(dso, ph->p_vaddr+ph->p_memsz,
425 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
429 static void *map_library(int fd, struct dso *dso)
431 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
432 void *allocated_buf=0;
434 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
435 size_t this_min, this_max;
440 unsigned char *map=MAP_FAILED, *base;
445 ssize_t l = read(fd, buf, sizeof buf);
448 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
450 phsize = eh->e_phentsize * eh->e_phnum;
451 if (phsize > sizeof buf - sizeof *eh) {
452 allocated_buf = malloc(phsize);
453 if (!allocated_buf) return 0;
454 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
455 if (l < 0) goto error;
456 if (l != phsize) goto noexec;
457 ph = ph0 = allocated_buf;
458 } else if (eh->e_phoff + phsize > l) {
459 l = pread(fd, buf+1, phsize, eh->e_phoff);
460 if (l < 0) goto error;
461 if (l != phsize) goto noexec;
462 ph = ph0 = (void *)(buf + 1);
464 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
466 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
467 if (ph->p_type == PT_DYNAMIC) {
469 } else if (ph->p_type == PT_TLS) {
470 tls_image = ph->p_vaddr;
471 dso->tls_align = ph->p_align;
472 dso->tls_len = ph->p_filesz;
473 dso->tls_size = ph->p_memsz;
474 } else if (ph->p_type == PT_GNU_RELRO) {
475 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
476 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
478 if (ph->p_type != PT_LOAD) continue;
479 if (ph->p_vaddr < addr_min) {
480 addr_min = ph->p_vaddr;
481 off_start = ph->p_offset;
482 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
483 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
484 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
486 if (ph->p_vaddr+ph->p_memsz > addr_max) {
487 addr_max = ph->p_vaddr+ph->p_memsz;
490 if (!dyn) goto noexec;
491 addr_max += PAGE_SIZE-1;
492 addr_max &= -PAGE_SIZE;
493 addr_min &= -PAGE_SIZE;
494 off_start &= -PAGE_SIZE;
495 map_len = addr_max - addr_min + off_start;
496 /* The first time, we map too much, possibly even more than
497 * the length of the file. This is okay because we will not
498 * use the invalid part; we just need to reserve the right
499 * amount of virtual address space to map over later. */
500 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
501 if (map==MAP_FAILED) goto error;
502 /* If the loaded file is not relocatable and the requested address is
503 * not available, then the load operation must fail. */
504 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
508 base = map - addr_min;
511 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
512 if (ph->p_type != PT_LOAD) continue;
513 /* Check if the programs headers are in this load segment, and
514 * if so, record the address for use by dl_iterate_phdr. */
515 if (!dso->phdr && eh->e_phoff >= ph->p_offset
516 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
517 dso->phdr = (void *)(base + ph->p_vaddr
518 + (eh->e_phoff-ph->p_offset));
519 dso->phnum = eh->e_phnum;
520 dso->phentsize = eh->e_phentsize;
522 /* Reuse the existing mapping for the lowest-address LOAD */
523 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
524 this_min = ph->p_vaddr & -PAGE_SIZE;
525 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
526 off_start = ph->p_offset & -PAGE_SIZE;
527 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
528 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
529 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
530 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
532 if (ph->p_memsz > ph->p_filesz) {
533 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
534 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
535 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
536 if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
540 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
541 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
542 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
547 dso->map_len = map_len;
549 dso->dynv = (void *)(base+dyn);
550 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
551 if (!runtime) reclaim_gaps(dso);
557 if (map!=MAP_FAILED) munmap(map, map_len);
562 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
567 s += strspn(s, ":\n");
568 l = strcspn(s, ":\n");
569 if (l-1 >= INT_MAX) return -1;
570 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) >= buf_size)
572 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
577 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
580 const char *s, *t, *origin;
582 if (p->rpath) return 0;
583 if (!p->rpath_orig) return -1;
584 if (!strchr(p->rpath_orig, '$')) {
585 p->rpath = p->rpath_orig;
590 while ((t=strchr(s, '$'))) {
591 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
596 if (n > SSIZE_MAX/PATH_MAX) return -1;
598 if (p->kernel_mapped) {
599 /* $ORIGIN searches cannot be performed for the main program
600 * when it is suid/sgid/AT_SECURE. This is because the
601 * pathname is under the control of the caller of execve.
602 * For libraries, however, $ORIGIN can be processed safely
603 * since the library's pathname came from a trusted source
604 * (either system paths or a call to dlopen). */
607 l = readlink("/proc/self/exe", buf, buf_size);
615 t = strrchr(origin, '/');
616 l = t ? t-origin : 0;
617 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
618 if (!p->rpath) return -1;
622 while ((t=strchr(s, '$'))) {
625 memcpy(d, origin, l);
627 /* It was determined previously that the '$' is followed
628 * either by "ORIGIN" or "{ORIGIN}". */
629 s = t + 7 + 2*(t[1]=='{');
635 static void decode_dyn(struct dso *p)
637 size_t dyn[DYN_CNT] = {0};
638 decode_vec(p->dynv, dyn, DYN_CNT);
639 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
640 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
641 if (dyn[0]&(1<<DT_HASH))
642 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
643 if (dyn[0]&(1<<DT_RPATH))
644 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
645 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
646 p->ghashtab = (void *)(p->base + *dyn);
647 if (search_vec(p->dynv, dyn, DT_VERSYM))
648 p->versym = (void *)(p->base + *dyn);
651 static struct dso *load_library(const char *name, struct dso *needed_by)
653 char buf[2*NAME_MAX+2];
654 const char *pathname;
656 struct dso *p, temp_dso = {0};
663 /* Catch and block attempts to reload the implementation itself */
664 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
665 static const char *rp, reserved[] =
666 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
667 char *z = strchr(name, '.');
670 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
673 /* Track which names have been resolved
674 * and only report each one once. */
675 static unsigned reported;
676 unsigned mask = 1U<<(rp-reserved);
677 if (!(reported & mask)) {
679 dprintf(1, "\t%s => %s (%p)\n",
688 if (!strcmp(name, ldso->name)) is_self = 1;
693 tail = ldso->next ? ldso->next : ldso;
697 if (strchr(name, '/')) {
699 fd = open(name, O_RDONLY|O_CLOEXEC);
701 /* Search for the name to see if it's already loaded */
702 for (p=head->next; p; p=p->next) {
703 if (p->shortname && !strcmp(p->shortname, name)) {
708 if (strlen(name) > NAME_MAX) return 0;
710 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
711 for (p=needed_by; fd < 0 && p; p=p->needed_by)
712 if (!fixup_rpath(p, buf, sizeof buf))
713 fd = path_open(name, p->rpath, buf, sizeof buf);
718 if (ldso->name[0]=='/') {
720 for (s=t=z=ldso->name; *s; s++)
721 if (*s=='/') z=t, t=s;
722 prefix_len = z-ldso->name;
723 if (prefix_len < PATH_MAX)
730 char etc_ldso_path[prefix_len + 1
731 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
732 snprintf(etc_ldso_path, sizeof etc_ldso_path,
733 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
734 (int)prefix_len, prefix);
735 FILE *f = fopen(etc_ldso_path, "rbe");
737 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
742 } else if (errno != ENOENT) {
746 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
747 fd = path_open(name, sys_path, buf, sizeof buf);
751 if (fd < 0) return 0;
752 if (fstat(fd, &st) < 0) {
756 for (p=head->next; p; p=p->next) {
757 if (p->dev == st.st_dev && p->ino == st.st_ino) {
758 /* If this library was previously loaded with a
759 * pathname but a search found the same inode,
760 * setup its shortname so it can be found by name. */
761 if (!p->shortname && pathname != name)
762 p->shortname = strrchr(p->name, '/')+1;
768 map = noload ? 0 : map_library(fd, &temp_dso);
772 /* Allocate storage for the new DSO. When there is TLS, this
773 * storage must include a reservation for all pre-existing
774 * threads to obtain copies of both the new TLS, and an
775 * extended DTV capable of storing an additional slot for
776 * the newly-loaded DSO. */
777 alloc_size = sizeof *p + strlen(pathname) + 1;
778 if (runtime && temp_dso.tls_image) {
779 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
780 + sizeof(void *) * (tls_cnt+3);
781 n_th = libc.threads_minus_1 + 1;
782 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
783 else alloc_size += n_th * per_th;
785 p = calloc(1, alloc_size);
787 munmap(map, temp_dso.map_len);
790 memcpy(p, &temp_dso, sizeof temp_dso);
795 p->needed_by = needed_by;
797 strcpy(p->name, pathname);
798 /* Add a shortname only if name arg was not an explicit pathname. */
799 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
801 if (runtime && !libc.has_thread_pointer) {
802 munmap(map, p->map_len);
807 p->tls_id = ++tls_cnt;
808 tls_align = MAXP2(tls_align, p->tls_align);
810 p->tls_offset = tls_offset + ( (tls_align-1) &
811 -(tls_offset + (uintptr_t)p->tls_image) );
812 tls_offset += p->tls_size;
814 tls_offset += p->tls_size + p->tls_align - 1;
815 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
817 p->tls_offset = tls_offset;
819 p->new_dtv = (void *)(-sizeof(size_t) &
820 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
821 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
828 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
833 static void load_deps(struct dso *p)
836 struct dso ***deps = &p->deps, **tmp, *dep;
837 for (; p; p=p->next) {
838 for (i=0; p->dynv[i]; i+=2) {
839 if (p->dynv[i] != DT_NEEDED) continue;
840 dep = load_library(p->strings + p->dynv[i+1], p);
842 error(errbuf, sizeof errbuf,
843 "Error loading shared library %s: %m (needed by %s)",
844 p->strings + p->dynv[i+1], p->name);
848 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
849 if (!tmp) longjmp(*rtld_fail, 1);
858 static void load_preload(char *s)
863 for ( ; *s && isspace(*s); s++);
864 for (z=s; *z && !isspace(*z); z++);
872 static void make_global(struct dso *p)
874 for (; p; p=p->next) p->global = 1;
877 static void reloc_all(struct dso *p)
879 size_t dyn[DYN_CNT] = {0};
880 for (; p; p=p->next) {
881 if (p->relocated) continue;
882 decode_vec(p->dynv, dyn, DYN_CNT);
883 #ifdef NEED_ARCH_RELOCS
884 do_arch_relocs(p, head);
886 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
887 2+(dyn[DT_PLTREL]==DT_RELA));
888 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
889 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
891 if (p->relro_start != p->relro_end &&
892 mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
893 error(errbuf, sizeof errbuf,
894 "Error relocating %s: RELRO protection failed: %m",
902 static void kernel_mapped_dso(struct dso *p)
904 size_t min_addr = -1, max_addr = 0, cnt;
906 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
907 if (ph->p_type == PT_DYNAMIC) {
908 p->dynv = (void *)(p->base + ph->p_vaddr);
909 } else if (ph->p_type == PT_GNU_RELRO) {
910 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
911 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
913 if (ph->p_type != PT_LOAD) continue;
914 if (ph->p_vaddr < min_addr)
915 min_addr = ph->p_vaddr;
916 if (ph->p_vaddr+ph->p_memsz > max_addr)
917 max_addr = ph->p_vaddr+ph->p_memsz;
919 min_addr &= -PAGE_SIZE;
920 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
921 p->map = p->base + min_addr;
922 p->map_len = max_addr - min_addr;
923 p->kernel_mapped = 1;
926 static void do_fini()
929 size_t dyn[DYN_CNT] = {0};
930 for (p=fini_head; p; p=p->fini_next) {
931 if (!p->constructed) continue;
932 decode_vec(p->dynv, dyn, DYN_CNT);
933 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
934 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
935 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
936 while (n--) ((void (*)(void))*--fn)();
938 #ifndef NO_LEGACY_INITFINI
939 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
940 ((void (*)(void))(p->base + dyn[DT_FINI]))();
945 static void do_init_fini(struct dso *p)
947 size_t dyn[DYN_CNT] = {0};
948 int need_locking = libc.threads_minus_1;
949 /* Allow recursive calls that arise when a library calls
950 * dlopen from one of its constructors, but block any
951 * other threads until all ctors have finished. */
952 if (need_locking) pthread_mutex_lock(&init_fini_lock);
953 for (; p; p=p->prev) {
954 if (p->constructed) continue;
956 decode_vec(p->dynv, dyn, DYN_CNT);
957 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
958 p->fini_next = fini_head;
961 #ifndef NO_LEGACY_INITFINI
962 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
963 ((void (*)(void))(p->base + dyn[DT_INIT]))();
965 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
966 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
967 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
968 while (n--) ((void (*)(void))*fn++)();
970 if (!need_locking && libc.threads_minus_1) {
972 pthread_mutex_lock(&init_fini_lock);
975 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
978 void _dl_debug_state(void)
984 pthread_t self = __pthread_self();
986 for (p=head; p; p=p->next) {
987 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
988 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
989 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
990 p->tls_size - p->tls_len);
991 if (p->tls_id == (size_t)self->dtv[0]) break;
995 void *__copy_tls(unsigned char *mem)
1000 void **dtv = (void *)mem;
1001 dtv[0] = (void *)tls_cnt;
1003 td = (void *)(dtv+1);
1009 mem += sizeof(void *) * (tls_cnt+1);
1010 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
1011 td = (pthread_t)mem;
1012 mem += sizeof(struct pthread);
1014 for (p=head; p; p=p->next) {
1015 if (!p->tls_id) continue;
1016 dtv[p->tls_id] = mem + p->tls_offset;
1017 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1020 mem += libc.tls_size - sizeof(struct pthread);
1021 mem -= (uintptr_t)mem & (tls_align-1);
1022 td = (pthread_t)mem;
1024 for (p=head; p; p=p->next) {
1025 if (!p->tls_id) continue;
1026 dtv[p->tls_id] = mem - p->tls_offset;
1027 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1034 void *__tls_get_addr(size_t *v)
1036 pthread_t self = __pthread_self();
1037 if (v[0]<=(size_t)self->dtv[0])
1038 return (char *)self->dtv[v[0]]+v[1];
1040 /* Block signals to make accessing new TLS async-signal-safe */
1042 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
1043 if (v[0]<=(size_t)self->dtv[0]) {
1044 pthread_sigmask(SIG_SETMASK, &set, 0);
1045 return (char *)self->dtv[v[0]]+v[1];
1048 /* This is safe without any locks held because, if the caller
1049 * is able to request the Nth entry of the DTV, the DSO list
1050 * must be valid at least that far out and it was synchronized
1051 * at program startup or by an already-completed call to dlopen. */
1053 for (p=head; p->tls_id != v[0]; p=p->next);
1055 /* Get new DTV space from new DSO if needed */
1056 if (v[0] > (size_t)self->dtv[0]) {
1057 void **newdtv = p->new_dtv +
1058 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1059 memcpy(newdtv, self->dtv,
1060 ((size_t)self->dtv[0]+1) * sizeof(void *));
1061 newdtv[0] = (void *)v[0];
1065 /* Get new TLS memory from all new DSOs up to the requested one */
1067 for (p=head; ; p=p->next) {
1068 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1069 mem = p->new_tls + (p->tls_size + p->tls_align)
1070 * a_fetch_add(&p->new_tls_idx,1);
1071 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
1073 self->dtv[p->tls_id] = mem;
1074 memcpy(mem, p->tls_image, p->tls_len);
1075 if (p->tls_id == v[0]) break;
1077 pthread_sigmask(SIG_SETMASK, &set, 0);
1081 static void update_tls_size()
1083 libc.tls_size = ALIGN(
1084 (1+tls_cnt) * sizeof(void *) +
1086 sizeof(struct pthread) +
1091 void *__dynlink(int argc, char **argv)
1093 size_t aux[AUX_CNT] = {0};
1097 static struct dso builtin_dsos[3];
1098 struct dso *const app = builtin_dsos+0;
1099 struct dso *const lib = builtin_dsos+1;
1100 struct dso *const vdso = builtin_dsos+2;
1101 char *env_preload=0;
1104 char **envp = argv+argc+1;
1107 /* Find aux vector just past environ[] */
1108 for (i=argc+1; argv[i]; i++)
1109 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
1110 env_path = argv[i]+16;
1111 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
1112 env_preload = argv[i]+11;
1113 auxv = (void *)(argv+i+1);
1115 decode_vec(auxv, aux, AUX_CNT);
1117 /* Only trust user/env if kernel says we're not suid/sgid */
1118 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1119 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1124 libc.page_size = aux[AT_PAGESZ];
1126 /* If the dynamic linker was invoked as a program itself, AT_BASE
1127 * will not be set. In that case, we assume the base address is
1128 * the start of the page containing the PHDRs; I don't know any
1129 * better approach... */
1130 if (!aux[AT_BASE]) {
1131 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
1132 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
1135 /* The dynamic linker load address is passed by the kernel
1136 * in the AUX vector, so this is easy. */
1137 lib->base = (void *)aux[AT_BASE];
1138 lib->name = lib->shortname = "libc.so";
1140 ehdr = (void *)lib->base;
1141 lib->phnum = ehdr->e_phnum;
1142 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
1143 lib->phentsize = ehdr->e_phentsize;
1144 kernel_mapped_dso(lib);
1148 size_t interp_off = 0;
1149 size_t tls_image = 0;
1150 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1151 app->phdr = phdr = (void *)aux[AT_PHDR];
1152 app->phnum = aux[AT_PHNUM];
1153 app->phentsize = aux[AT_PHENT];
1154 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1155 if (phdr->p_type == PT_PHDR)
1156 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1157 else if (phdr->p_type == PT_INTERP)
1158 interp_off = (size_t)phdr->p_vaddr;
1159 else if (phdr->p_type == PT_TLS) {
1160 tls_image = phdr->p_vaddr;
1161 app->tls_len = phdr->p_filesz;
1162 app->tls_size = phdr->p_memsz;
1163 app->tls_align = phdr->p_align;
1166 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
1167 if (interp_off) lib->name = (char *)app->base + interp_off;
1168 if ((aux[0] & (1UL<<AT_EXECFN))
1169 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1170 app->name = (char *)aux[AT_EXECFN];
1172 app->name = argv[0];
1173 kernel_mapped_dso(app);
1176 char *ldname = argv[0];
1177 size_t l = strlen(ldname);
1178 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1179 *argv++ = (void *)-1;
1180 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1181 char *opt = argv[0]+2;
1182 *argv++ = (void *)-1;
1185 } else if (!memcmp(opt, "list", 5)) {
1187 } else if (!memcmp(opt, "library-path", 12)) {
1188 if (opt[12]=='=') env_path = opt+13;
1189 else if (opt[12]) *argv = 0;
1190 else if (*argv) env_path = *argv++;
1191 } else if (!memcmp(opt, "preload", 7)) {
1192 if (opt[7]=='=') env_preload = opt+8;
1193 else if (opt[7]) *argv = 0;
1194 else if (*argv) env_preload = *argv++;
1198 argv[-1] = (void *)-1;
1201 dprintf(2, "musl libc\n"
1203 "Dynamic Program Loader\n"
1204 "Usage: %s [options] [--] pathname%s\n",
1205 __libc_get_version(), ldname,
1206 ldd_mode ? "" : " [args]");
1209 fd = open(argv[0], O_RDONLY);
1211 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1215 ehdr = (void *)map_library(fd, app);
1217 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1223 app->name = argv[0];
1224 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
1225 /* Find the name that would have been used for the dynamic
1226 * linker had ldd not taken its place. */
1228 for (i=0; i<app->phnum; i++) {
1229 if (app->phdr[i].p_type == PT_INTERP)
1230 lib->name = (void *)(app->base
1231 + app->phdr[i].p_vaddr);
1233 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1236 if (app->tls_size) {
1237 app->tls_id = tls_cnt = 1;
1239 app->tls_offset = 0;
1240 tls_offset = app->tls_size
1241 + ( -((uintptr_t)app->tls_image + app->tls_size)
1242 & (app->tls_align-1) );
1244 tls_offset = app->tls_offset = app->tls_size
1245 + ( -((uintptr_t)app->tls_image + app->tls_size)
1246 & (app->tls_align-1) );
1248 tls_align = MAXP2(tls_align, app->tls_align);
1253 /* Attach to vdso, if provided by the kernel */
1254 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1255 ehdr = (void *)vdso_base;
1256 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1257 vdso->phnum = ehdr->e_phnum;
1258 vdso->phentsize = ehdr->e_phentsize;
1259 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1260 if (phdr->p_type == PT_DYNAMIC)
1261 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1262 if (phdr->p_type == PT_LOAD)
1263 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1266 vdso->shortname = "linux-gate.so.1";
1273 /* Initial dso chain consists only of the app. We temporarily
1274 * append the dynamic linker/libc so we can relocate it, then
1275 * restore the initial chain in preparation for loading third
1276 * party libraries (preload/needed). */
1283 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1285 /* Donate unused parts of app and library mapping to malloc */
1289 /* Load preload/needed libraries, add their symbols to the global
1290 * namespace, and perform all remaining relocations. The main
1291 * program must be relocated LAST since it may contain copy
1292 * relocations which depend on libraries' relocations. */
1293 if (env_preload) load_preload(env_preload);
1297 #ifndef DYNAMIC_IS_RO
1298 for (i=0; app->dynv[i]; i+=2)
1299 if (app->dynv[i]==DT_DEBUG)
1300 app->dynv[i+1] = (size_t)&debug;
1303 reloc_all(app->next);
1307 if (libc.tls_size > sizeof builtin_tls) {
1308 initial_tls = calloc(libc.tls_size, 1);
1310 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1311 argv[0], libc.tls_size);
1315 initial_tls = builtin_tls;
1317 if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) {
1318 dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]);
1321 static_tls_cnt = tls_cnt;
1323 if (ldso_fail) _exit(127);
1324 if (ldd_mode) _exit(0);
1326 /* Switch to runtime mode: any further failures in the dynamic
1327 * linker are a reportable failure rather than a fatal startup
1328 * error. If the dynamic loader (dlopen) will not be used, free
1329 * all memory used by the dynamic linker. */
1333 debug.bp = _dl_debug_state;
1335 debug.base = lib->base;
1339 __init_libc(envp, argv[0]);
1344 return (void *)aux[AT_ENTRY];
1347 void *dlopen(const char *file, int mode)
1349 struct dso *volatile p, *orig_tail, *next;
1350 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1355 if (!file) return head;
1357 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1358 pthread_rwlock_wrlock(&lock);
1362 orig_tls_cnt = tls_cnt;
1363 orig_tls_offset = tls_offset;
1364 orig_tls_align = tls_align;
1366 noload = mode & RTLD_NOLOAD;
1369 if (setjmp(*rtld_fail)) {
1370 /* Clean up anything new that was (partially) loaded */
1371 if (p && p->deps) for (i=0; p->deps[i]; i++)
1372 if (p->deps[i]->global < 0)
1373 p->deps[i]->global = 0;
1374 for (p=orig_tail->next; p; p=next) {
1376 munmap(p->map, p->map_len);
1377 while (p->td_index) {
1378 void *tmp = p->td_index->next;
1385 tls_cnt = orig_tls_cnt;
1386 tls_offset = orig_tls_offset;
1387 tls_align = orig_tls_align;
1393 } else p = load_library(file, head);
1396 snprintf(errbuf, sizeof errbuf, noload ?
1397 "Library %s is not already loaded" :
1398 "Error loading shared library %s: %m",
1404 /* First load handling */
1407 if (p->deps) for (i=0; p->deps[i]; i++)
1408 if (!p->deps[i]->global)
1409 p->deps[i]->global = -1;
1410 if (!p->global) p->global = -1;
1412 if (p->deps) for (i=0; p->deps[i]; i++)
1413 if (p->deps[i]->global < 0)
1414 p->deps[i]->global = 0;
1415 if (p->global < 0) p->global = 0;
1418 if (mode & RTLD_GLOBAL) {
1419 if (p->deps) for (i=0; p->deps[i]; i++)
1420 p->deps[i]->global = 1;
1430 pthread_rwlock_unlock(&lock);
1431 if (p) do_init_fini(orig_tail);
1432 pthread_setcancelstate(cs, 0);
1436 static int invalid_dso_handle(void *h)
1439 for (p=head; p; p=p->next) if (h==p) return 0;
1440 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1445 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1448 uint32_t h = 0, gh = 0;
1450 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1451 if (p == RTLD_DEFAULT) {
1453 } else if (p == RTLD_NEXT) {
1454 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1458 struct symdef def = find_sym(p, s, 0);
1459 if (!def.sym) goto failed;
1460 if ((def.sym->st_info&0xf) == STT_TLS)
1461 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1462 return def.dso->base + def.sym->st_value;
1464 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1468 sym = gnu_lookup(s, gh, p);
1471 sym = sysv_lookup(s, h, p);
1473 if (sym && (sym->st_info&0xf) == STT_TLS)
1474 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1475 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1476 return p->base + sym->st_value;
1477 if (p->deps) for (i=0; p->deps[i]; i++) {
1478 if (p->deps[i]->ghashtab) {
1479 if (!gh) gh = gnu_hash(s);
1480 sym = gnu_lookup(s, gh, p->deps[i]);
1482 if (!h) h = sysv_hash(s);
1483 sym = sysv_lookup(s, h, p->deps[i]);
1485 if (sym && (sym->st_info&0xf) == STT_TLS)
1486 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1487 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1488 return p->deps[i]->base + sym->st_value;
1492 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1496 int __dladdr(const void *addr, Dl_info *info)
1506 pthread_rwlock_rdlock(&lock);
1507 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1508 pthread_rwlock_unlock(&lock);
1513 strings = p->strings;
1515 nsym = p->hashtab[1];
1519 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1520 sym += p->ghashtab[1];
1521 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1522 if (buckets[i] > nsym)
1526 nsym -= p->ghashtab[1];
1527 hashval = buckets + p->ghashtab[0] + nsym;
1529 while (!(*hashval++ & 1));
1533 for (; nsym; nsym--, sym++) {
1535 && (1<<(sym->st_info&0xf) & OK_TYPES)
1536 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1537 void *symaddr = p->base + sym->st_value;
1538 if (symaddr > addr || symaddr < best)
1541 bestname = strings + sym->st_name;
1542 if (addr == symaddr)
1547 if (!best) return 0;
1549 info->dli_fname = p->name;
1550 info->dli_fbase = p->base;
1551 info->dli_sname = bestname;
1552 info->dli_saddr = best;
1557 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1560 pthread_rwlock_rdlock(&lock);
1561 res = do_dlsym(p, s, ra);
1562 pthread_rwlock_unlock(&lock);
1566 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1568 struct dso *current;
1569 struct dl_phdr_info info;
1571 for(current = head; current;) {
1572 info.dlpi_addr = (uintptr_t)current->base;
1573 info.dlpi_name = current->name;
1574 info.dlpi_phdr = current->phdr;
1575 info.dlpi_phnum = current->phnum;
1576 info.dlpi_adds = gencnt;
1578 info.dlpi_tls_modid = current->tls_id;
1579 info.dlpi_tls_data = current->tls_image;
1581 ret = (callback)(&info, sizeof (info), data);
1583 if (ret != 0) break;
1585 pthread_rwlock_rdlock(&lock);
1586 current = current->next;
1587 pthread_rwlock_unlock(&lock);
1592 static int invalid_dso_handle(void *h)
1594 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1598 void *dlopen(const char *file, int mode)
1602 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1606 int __dladdr (const void *addr, Dl_info *info)
1612 int __dlinfo(void *dso, int req, void *res)
1614 if (invalid_dso_handle(dso)) return -1;
1615 if (req != RTLD_DI_LINKMAP) {
1616 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1620 *(struct link_map **)res = dso;
1626 if (!errflag) return 0;
1631 int dlclose(void *p)
1633 return invalid_dso_handle(p);