18 #include "pthread_impl.h"
22 static char errbuf[128];
26 #if ULONG_MAX == 0xffffffff
27 typedef Elf32_Ehdr Ehdr;
28 typedef Elf32_Phdr Phdr;
29 typedef Elf32_Sym Sym;
30 #define R_TYPE(x) ((x)&255)
31 #define R_SYM(x) ((x)>>8)
33 typedef Elf64_Ehdr Ehdr;
34 typedef Elf64_Phdr Phdr;
35 typedef Elf64_Sym Sym;
36 #define R_TYPE(x) ((x)&0xffffffff)
37 #define R_SYM(x) ((x)>>32)
40 #define MAXP2(a,b) (-(-(a)&-(b)))
41 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
55 struct dso *next, *prev;
74 struct dso **deps, *needed_by;
75 char *rpath_orig, *rpath;
77 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
78 size_t relro_start, relro_end;
80 unsigned char *new_tls;
81 int new_dtv_idx, new_tls_idx;
82 struct dso *fini_next;
102 REL_TLS, /* everything past here is TLS */
111 int __init_tp(void *);
112 void __init_libc(char **, char *);
114 const char *__libc_get_version(void);
116 static struct dso *head, *tail, *ldso, *fini_head;
117 static char *env_path, *sys_path;
118 static unsigned long long gencnt;
121 static int ldso_fail;
123 static jmp_buf *rtld_fail;
124 static pthread_rwlock_t lock;
125 static struct debug debug;
126 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
127 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
128 static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)];
130 struct debug *_dl_debug_addr = &debug;
135 static void decode_vec(size_t *v, size_t *a, size_t cnt)
137 memset(a, 0, cnt*sizeof(size_t));
138 for (; v[0]; v+=2) if (v[0]<cnt) {
144 static int search_vec(size_t *v, size_t *r, size_t key)
146 for (; v[0]!=key; v+=2)
152 static uint32_t sysv_hash(const char *s0)
154 const unsigned char *s = (void *)s0;
160 return h & 0xfffffff;
163 static uint32_t gnu_hash(const char *s0)
165 const unsigned char *s = (void *)s0;
166 uint_fast32_t h = 5381;
172 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
175 Sym *syms = dso->syms;
176 uint32_t *hashtab = dso->hashtab;
177 char *strings = dso->strings;
178 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
179 if ((!dso->versym || dso->versym[i] >= 0)
180 && (!strcmp(s, strings+syms[i].st_name)))
186 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
188 Sym *syms = dso->syms;
189 char *strings = dso->strings;
190 uint32_t *hashtab = dso->ghashtab;
191 uint32_t nbuckets = hashtab[0];
192 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
195 uint32_t i = buckets[h1 % nbuckets];
199 hashval = buckets + nbuckets + (i - hashtab[1]);
201 for (h1 |= 1; ; i++) {
203 if ((!dso->versym || dso->versym[i] >= 0)
204 && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
212 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
213 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
215 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
217 uint32_t h = 0, gh = 0;
218 struct symdef def = {0};
219 for (; dso; dso=dso->next) {
221 if (!dso->global) continue;
223 if (!gh) gh = gnu_hash(s);
224 sym = gnu_lookup(s, gh, dso);
226 if (!h) h = sysv_hash(s);
227 sym = sysv_lookup(s, h, dso);
231 if (need_def || (sym->st_info&0xf) == STT_TLS)
234 if ((sym->st_info&0xf) != STT_TLS)
236 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
237 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
239 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
242 if (sym->st_info>>4 == STB_GLOBAL) break;
247 #define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT)
249 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
251 unsigned char *base = dso->base;
252 Sym *syms = dso->syms;
253 char *strings = dso->strings;
265 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
266 astype = R_TYPE(rel[1]);
267 if (!astype) continue;
268 type = remap_rel(astype);
270 snprintf(errbuf, sizeof errbuf,
271 "Error relocating %s: unsupported relocation type %d",
273 if (runtime) longjmp(*rtld_fail, 1);
274 dprintf(2, "%s\n", errbuf);
278 sym_index = R_SYM(rel[1]);
279 reloc_addr = (void *)(base + rel[0]);
281 sym = syms + sym_index;
282 name = strings + sym->st_name;
283 ctx = type==REL_COPY ? head->next : head;
284 def = find_sym(ctx, name, type==REL_PLT);
285 if (!def.sym && (sym->st_shndx != SHN_UNDEF
286 || sym->st_info>>4 != STB_WEAK)) {
287 snprintf(errbuf, sizeof errbuf,
288 "Error relocating %s: %s: symbol not found",
290 if (runtime) longjmp(*rtld_fail, 1);
291 dprintf(2, "%s\n", errbuf);
301 addend = stride>2 ? rel[2]
302 : (1<<type & NO_INLINE_ADDEND) ? 0
305 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
306 tls_val = def.sym ? def.sym->st_value : 0;
310 addend -= (size_t)reloc_addr;
314 *reloc_addr = sym_val + addend;
317 *reloc_addr = (size_t)base + addend;
320 if (sym) *reloc_addr = sym_val + addend;
321 else *reloc_addr = (size_t)base + addend;
324 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
327 *(uint32_t *)reloc_addr = sym_val + addend
328 - (size_t)reloc_addr;
331 *reloc_addr = def.dso->tls_id;
334 *reloc_addr = tls_val + addend;
338 *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
342 *reloc_addr = tls_val - def.dso->tls_offset + addend;
345 *reloc_addr = def.dso->tls_offset - tls_val + addend;
352 /* A huge hack: to make up for the wastefulness of shared libraries
353 * needing at least a page of dirty memory even if they have no global
354 * data, we reclaim the gaps at the beginning and end of writable maps
355 * and "donate" them to the heap by setting up minimal malloc
356 * structures and then freeing them. */
358 static void reclaim(struct dso *dso, size_t start, size_t end)
361 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
362 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
363 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
364 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
365 if (start>end || end-start < 4*sizeof(size_t)) return;
366 a = (size_t *)(dso->base + start);
367 z = (size_t *)(dso->base + end);
369 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
374 static void reclaim_gaps(struct dso *dso)
376 Phdr *ph = dso->phdr;
377 size_t phcnt = dso->phnum;
379 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
380 if (ph->p_type!=PT_LOAD) continue;
381 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
382 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
383 reclaim(dso, ph->p_vaddr+ph->p_memsz,
384 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
388 static void *map_library(int fd, struct dso *dso)
390 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
391 void *allocated_buf=0;
393 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
394 size_t this_min, this_max;
399 unsigned char *map=MAP_FAILED, *base;
404 ssize_t l = read(fd, buf, sizeof buf);
407 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
409 phsize = eh->e_phentsize * eh->e_phnum;
410 if (phsize > sizeof buf - sizeof *eh) {
411 allocated_buf = malloc(phsize);
412 if (!allocated_buf) return 0;
413 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
414 if (l < 0) goto error;
415 if (l != phsize) goto noexec;
416 ph = ph0 = allocated_buf;
417 } else if (eh->e_phoff + phsize > l) {
418 l = pread(fd, buf+1, phsize, eh->e_phoff);
419 if (l < 0) goto error;
420 if (l != phsize) goto noexec;
421 ph = ph0 = (void *)(buf + 1);
423 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
425 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
426 if (ph->p_type == PT_DYNAMIC) {
428 } else if (ph->p_type == PT_TLS) {
429 tls_image = ph->p_vaddr;
430 dso->tls_align = ph->p_align;
431 dso->tls_len = ph->p_filesz;
432 dso->tls_size = ph->p_memsz;
433 } else if (ph->p_type == PT_GNU_RELRO) {
434 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
435 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
437 if (ph->p_type != PT_LOAD) continue;
438 if (ph->p_vaddr < addr_min) {
439 addr_min = ph->p_vaddr;
440 off_start = ph->p_offset;
441 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
442 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
443 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
445 if (ph->p_vaddr+ph->p_memsz > addr_max) {
446 addr_max = ph->p_vaddr+ph->p_memsz;
449 if (!dyn) goto noexec;
450 addr_max += PAGE_SIZE-1;
451 addr_max &= -PAGE_SIZE;
452 addr_min &= -PAGE_SIZE;
453 off_start &= -PAGE_SIZE;
454 map_len = addr_max - addr_min + off_start;
455 /* The first time, we map too much, possibly even more than
456 * the length of the file. This is okay because we will not
457 * use the invalid part; we just need to reserve the right
458 * amount of virtual address space to map over later. */
459 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
460 if (map==MAP_FAILED) goto error;
461 /* If the loaded file is not relocatable and the requested address is
462 * not available, then the load operation must fail. */
463 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
467 base = map - addr_min;
470 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
471 if (ph->p_type != PT_LOAD) continue;
472 /* Check if the programs headers are in this load segment, and
473 * if so, record the address for use by dl_iterate_phdr. */
474 if (!dso->phdr && eh->e_phoff >= ph->p_offset
475 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
476 dso->phdr = (void *)(base + ph->p_vaddr
477 + (eh->e_phoff-ph->p_offset));
478 dso->phnum = eh->e_phnum;
479 dso->phentsize = eh->e_phentsize;
481 /* Reuse the existing mapping for the lowest-address LOAD */
482 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
483 this_min = ph->p_vaddr & -PAGE_SIZE;
484 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
485 off_start = ph->p_offset & -PAGE_SIZE;
486 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
487 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
488 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
489 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
491 if (ph->p_memsz > ph->p_filesz) {
492 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
493 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
494 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
495 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)
499 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
500 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
501 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
506 dso->map_len = map_len;
508 dso->dynv = (void *)(base+dyn);
509 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
510 if (!runtime) reclaim_gaps(dso);
516 if (map!=MAP_FAILED) munmap(map, map_len);
521 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
526 s += strspn(s, ":\n");
527 l = strcspn(s, ":\n");
528 if (l-1 >= INT_MAX) return -1;
529 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) >= buf_size)
531 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
536 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
539 const char *s, *t, *origin;
541 if (p->rpath) return 0;
542 if (!p->rpath_orig) return -1;
543 if (!strchr(p->rpath_orig, '$')) {
544 p->rpath = p->rpath_orig;
549 while ((t=strchr(s, '$'))) {
550 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
555 if (n > SSIZE_MAX/PATH_MAX) return -1;
557 if (p->kernel_mapped) {
558 /* $ORIGIN searches cannot be performed for the main program
559 * when it is suid/sgid/AT_SECURE. This is because the
560 * pathname is under the control of the caller of execve.
561 * For libraries, however, $ORIGIN can be processed safely
562 * since the library's pathname came from a trusted source
563 * (either system paths or a call to dlopen). */
566 l = readlink("/proc/self/exe", buf, buf_size);
574 t = strrchr(origin, '/');
575 l = t ? t-origin : 0;
576 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
577 if (!p->rpath) return -1;
581 while ((t=strchr(s, '$'))) {
584 memcpy(d, origin, l);
586 /* It was determined previously that the '$' is followed
587 * either by "ORIGIN" or "{ORIGIN}". */
588 s = t + 7 + 2*(t[1]=='{');
594 static void decode_dyn(struct dso *p)
596 size_t dyn[DYN_CNT] = {0};
597 decode_vec(p->dynv, dyn, DYN_CNT);
598 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
599 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
600 if (dyn[0]&(1<<DT_HASH))
601 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
602 if (dyn[0]&(1<<DT_RPATH))
603 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
604 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
605 p->ghashtab = (void *)(p->base + *dyn);
606 if (search_vec(p->dynv, dyn, DT_VERSYM))
607 p->versym = (void *)(p->base + *dyn);
610 static struct dso *load_library(const char *name, struct dso *needed_by)
612 char buf[2*NAME_MAX+2];
613 const char *pathname;
615 struct dso *p, temp_dso = {0};
622 /* Catch and block attempts to reload the implementation itself */
623 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
624 static const char *rp, reserved[] =
625 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
626 char *z = strchr(name, '.');
629 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
632 /* Track which names have been resolved
633 * and only report each one once. */
634 static unsigned reported;
635 unsigned mask = 1U<<(rp-reserved);
636 if (!(reported & mask)) {
638 dprintf(1, "\t%s => %s (%p)\n",
647 if (!strcmp(name, ldso->name)) is_self = 1;
652 tail = ldso->next ? ldso->next : ldso;
656 if (strchr(name, '/')) {
658 fd = open(name, O_RDONLY|O_CLOEXEC);
660 /* Search for the name to see if it's already loaded */
661 for (p=head->next; p; p=p->next) {
662 if (p->shortname && !strcmp(p->shortname, name)) {
667 if (strlen(name) > NAME_MAX) return 0;
669 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
670 for (p=needed_by; fd < 0 && p; p=p->needed_by)
671 if (!fixup_rpath(p, buf, sizeof buf))
672 fd = path_open(name, p->rpath, buf, sizeof buf);
677 if (ldso->name[0]=='/') {
679 for (s=t=z=ldso->name; *s; s++)
680 if (*s=='/') z=t, t=s;
681 prefix_len = z-ldso->name;
682 if (prefix_len < PATH_MAX)
689 char etc_ldso_path[prefix_len + 1
690 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
691 snprintf(etc_ldso_path, sizeof etc_ldso_path,
692 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
693 (int)prefix_len, prefix);
694 FILE *f = fopen(etc_ldso_path, "rbe");
696 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
701 } else if (errno != ENOENT) {
705 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
706 fd = path_open(name, sys_path, buf, sizeof buf);
710 if (fd < 0) return 0;
711 if (fstat(fd, &st) < 0) {
715 for (p=head->next; p; p=p->next) {
716 if (p->dev == st.st_dev && p->ino == st.st_ino) {
717 /* If this library was previously loaded with a
718 * pathname but a search found the same inode,
719 * setup its shortname so it can be found by name. */
720 if (!p->shortname && pathname != name)
721 p->shortname = strrchr(p->name, '/')+1;
727 map = noload ? 0 : map_library(fd, &temp_dso);
731 /* Allocate storage for the new DSO. When there is TLS, this
732 * storage must include a reservation for all pre-existing
733 * threads to obtain copies of both the new TLS, and an
734 * extended DTV capable of storing an additional slot for
735 * the newly-loaded DSO. */
736 alloc_size = sizeof *p + strlen(pathname) + 1;
737 if (runtime && temp_dso.tls_image) {
738 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
739 + sizeof(void *) * (tls_cnt+3);
740 n_th = libc.threads_minus_1 + 1;
741 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
742 else alloc_size += n_th * per_th;
744 p = calloc(1, alloc_size);
746 munmap(map, temp_dso.map_len);
749 memcpy(p, &temp_dso, sizeof temp_dso);
754 p->needed_by = needed_by;
756 strcpy(p->name, pathname);
757 /* Add a shortname only if name arg was not an explicit pathname. */
758 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
760 if (runtime && !libc.has_thread_pointer) {
761 munmap(map, p->map_len);
766 p->tls_id = ++tls_cnt;
767 tls_align = MAXP2(tls_align, p->tls_align);
769 p->tls_offset = tls_offset + ( (tls_align-1) &
770 -(tls_offset + (uintptr_t)p->tls_image) );
771 tls_offset += p->tls_size;
773 tls_offset += p->tls_size + p->tls_align - 1;
774 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
776 p->tls_offset = tls_offset;
778 p->new_dtv = (void *)(-sizeof(size_t) &
779 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
780 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
787 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
792 static void load_deps(struct dso *p)
795 struct dso ***deps = &p->deps, **tmp, *dep;
796 for (; p; p=p->next) {
797 for (i=0; p->dynv[i]; i+=2) {
798 if (p->dynv[i] != DT_NEEDED) continue;
799 dep = load_library(p->strings + p->dynv[i+1], p);
801 snprintf(errbuf, sizeof errbuf,
802 "Error loading shared library %s: %m (needed by %s)",
803 p->strings + p->dynv[i+1], p->name);
804 if (runtime) longjmp(*rtld_fail, 1);
805 dprintf(2, "%s\n", errbuf);
810 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
811 if (!tmp) longjmp(*rtld_fail, 1);
820 static void load_preload(char *s)
825 for ( ; *s && isspace(*s); s++);
826 for (z=s; *z && !isspace(*z); z++);
834 static void make_global(struct dso *p)
836 for (; p; p=p->next) p->global = 1;
839 static void reloc_all(struct dso *p)
841 size_t dyn[DYN_CNT] = {0};
842 for (; p; p=p->next) {
843 if (p->relocated) continue;
844 decode_vec(p->dynv, dyn, DYN_CNT);
845 #ifdef NEED_ARCH_RELOCS
846 do_arch_relocs(p, head);
848 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
849 2+(dyn[DT_PLTREL]==DT_RELA));
850 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
851 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
853 if (p->relro_start != p->relro_end &&
854 mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
855 snprintf(errbuf, sizeof errbuf,
856 "Error relocating %s: RELRO protection failed: %m",
858 if (runtime) longjmp(*rtld_fail, 1);
859 dprintf(2, "%s\n", errbuf);
867 static void kernel_mapped_dso(struct dso *p)
869 size_t min_addr = -1, max_addr = 0, cnt;
871 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
872 if (ph->p_type == PT_DYNAMIC) {
873 p->dynv = (void *)(p->base + ph->p_vaddr);
874 } else if (ph->p_type == PT_GNU_RELRO) {
875 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
876 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
878 if (ph->p_type != PT_LOAD) continue;
879 if (ph->p_vaddr < min_addr)
880 min_addr = ph->p_vaddr;
881 if (ph->p_vaddr+ph->p_memsz > max_addr)
882 max_addr = ph->p_vaddr+ph->p_memsz;
884 min_addr &= -PAGE_SIZE;
885 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
886 p->map = p->base + min_addr;
887 p->map_len = max_addr - min_addr;
888 p->kernel_mapped = 1;
891 static void do_fini()
894 size_t dyn[DYN_CNT] = {0};
895 for (p=fini_head; p; p=p->fini_next) {
896 if (!p->constructed) continue;
897 decode_vec(p->dynv, dyn, DYN_CNT);
898 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
899 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
900 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
901 while (n--) ((void (*)(void))*--fn)();
903 #ifndef NO_LEGACY_INITFINI
904 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
905 ((void (*)(void))(p->base + dyn[DT_FINI]))();
910 static void do_init_fini(struct dso *p)
912 size_t dyn[DYN_CNT] = {0};
913 int need_locking = libc.threads_minus_1;
914 /* Allow recursive calls that arise when a library calls
915 * dlopen from one of its constructors, but block any
916 * other threads until all ctors have finished. */
917 if (need_locking) pthread_mutex_lock(&init_fini_lock);
918 for (; p; p=p->prev) {
919 if (p->constructed) continue;
921 decode_vec(p->dynv, dyn, DYN_CNT);
922 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
923 p->fini_next = fini_head;
926 #ifndef NO_LEGACY_INITFINI
927 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
928 ((void (*)(void))(p->base + dyn[DT_INIT]))();
930 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
931 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
932 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
933 while (n--) ((void (*)(void))*fn++)();
935 if (!need_locking && libc.threads_minus_1) {
937 pthread_mutex_lock(&init_fini_lock);
940 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
943 void _dl_debug_state(void)
949 pthread_t self = __pthread_self();
951 for (p=head; p; p=p->next) {
952 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
953 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
954 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
955 p->tls_size - p->tls_len);
956 if (p->tls_id == (size_t)self->dtv[0]) break;
960 void *__copy_tls(unsigned char *mem)
965 void **dtv = (void *)mem;
966 dtv[0] = (void *)tls_cnt;
968 td = (void *)(dtv+1);
974 mem += sizeof(void *) * (tls_cnt+1);
975 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
977 mem += sizeof(struct pthread);
979 for (p=head; p; p=p->next) {
980 if (!p->tls_id) continue;
981 dtv[p->tls_id] = mem + p->tls_offset;
982 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
985 mem += libc.tls_size - sizeof(struct pthread);
986 mem -= (uintptr_t)mem & (tls_align-1);
989 for (p=head; p; p=p->next) {
990 if (!p->tls_id) continue;
991 dtv[p->tls_id] = mem - p->tls_offset;
992 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
999 void *__tls_get_addr(size_t *v)
1001 pthread_t self = __pthread_self();
1002 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
1003 return (char *)self->dtv[v[0]]+v[1];
1005 /* Block signals to make accessing new TLS async-signal-safe */
1007 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
1008 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
1009 pthread_sigmask(SIG_SETMASK, &set, 0);
1010 return (char *)self->dtv[v[0]]+v[1];
1013 /* This is safe without any locks held because, if the caller
1014 * is able to request the Nth entry of the DTV, the DSO list
1015 * must be valid at least that far out and it was synchronized
1016 * at program startup or by an already-completed call to dlopen. */
1018 for (p=head; p->tls_id != v[0]; p=p->next);
1020 /* Get new DTV space from new DSO if needed */
1021 if (v[0] > (size_t)self->dtv[0]) {
1022 void **newdtv = p->new_dtv +
1023 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1024 memcpy(newdtv, self->dtv,
1025 ((size_t)self->dtv[0]+1) * sizeof(void *));
1026 newdtv[0] = (void *)v[0];
1030 /* Get new TLS memory from new DSO */
1031 unsigned char *mem = p->new_tls +
1032 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
1033 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
1034 self->dtv[v[0]] = mem;
1035 memcpy(mem, p->tls_image, p->tls_len);
1036 pthread_sigmask(SIG_SETMASK, &set, 0);
1040 static void update_tls_size()
1042 libc.tls_size = ALIGN(
1043 (1+tls_cnt) * sizeof(void *) +
1045 sizeof(struct pthread) +
1050 void *__dynlink(int argc, char **argv)
1052 size_t aux[AUX_CNT] = {0};
1056 static struct dso builtin_dsos[3];
1057 struct dso *const app = builtin_dsos+0;
1058 struct dso *const lib = builtin_dsos+1;
1059 struct dso *const vdso = builtin_dsos+2;
1060 char *env_preload=0;
1063 char **envp = argv+argc+1;
1066 /* Find aux vector just past environ[] */
1067 for (i=argc+1; argv[i]; i++)
1068 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
1069 env_path = argv[i]+16;
1070 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
1071 env_preload = argv[i]+11;
1072 auxv = (void *)(argv+i+1);
1074 decode_vec(auxv, aux, AUX_CNT);
1076 /* Only trust user/env if kernel says we're not suid/sgid */
1077 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1078 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1083 libc.page_size = aux[AT_PAGESZ];
1085 /* If the dynamic linker was invoked as a program itself, AT_BASE
1086 * will not be set. In that case, we assume the base address is
1087 * the start of the page containing the PHDRs; I don't know any
1088 * better approach... */
1089 if (!aux[AT_BASE]) {
1090 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
1091 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
1094 /* The dynamic linker load address is passed by the kernel
1095 * in the AUX vector, so this is easy. */
1096 lib->base = (void *)aux[AT_BASE];
1097 lib->name = lib->shortname = "libc.so";
1099 ehdr = (void *)lib->base;
1100 lib->phnum = ehdr->e_phnum;
1101 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
1102 lib->phentsize = ehdr->e_phentsize;
1103 kernel_mapped_dso(lib);
1107 size_t interp_off = 0;
1108 size_t tls_image = 0;
1109 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1110 app->phdr = phdr = (void *)aux[AT_PHDR];
1111 app->phnum = aux[AT_PHNUM];
1112 app->phentsize = aux[AT_PHENT];
1113 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1114 if (phdr->p_type == PT_PHDR)
1115 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1116 else if (phdr->p_type == PT_INTERP)
1117 interp_off = (size_t)phdr->p_vaddr;
1118 else if (phdr->p_type == PT_TLS) {
1119 tls_image = phdr->p_vaddr;
1120 app->tls_len = phdr->p_filesz;
1121 app->tls_size = phdr->p_memsz;
1122 app->tls_align = phdr->p_align;
1125 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
1126 if (interp_off) lib->name = (char *)app->base + interp_off;
1127 if ((aux[0] & (1UL<<AT_EXECFN))
1128 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1129 app->name = (char *)aux[AT_EXECFN];
1131 app->name = argv[0];
1132 kernel_mapped_dso(app);
1135 char *ldname = argv[0];
1136 size_t l = strlen(ldname);
1137 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1138 *argv++ = (void *)-1;
1139 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1140 char *opt = argv[0]+2;
1141 *argv++ = (void *)-1;
1144 } else if (!memcmp(opt, "list", 5)) {
1146 } else if (!memcmp(opt, "library-path", 12)) {
1147 if (opt[12]=='=') env_path = opt+13;
1148 else if (opt[12]) *argv = 0;
1149 else if (*argv) env_path = *argv++;
1150 } else if (!memcmp(opt, "preload", 7)) {
1151 if (opt[7]=='=') env_preload = opt+8;
1152 else if (opt[7]) *argv = 0;
1153 else if (*argv) env_preload = *argv++;
1157 argv[-1] = (void *)-1;
1160 dprintf(2, "musl libc\n"
1162 "Dynamic Program Loader\n"
1163 "Usage: %s [options] [--] pathname%s\n",
1164 __libc_get_version(), ldname,
1165 ldd_mode ? "" : " [args]");
1168 fd = open(argv[0], O_RDONLY);
1170 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1174 ehdr = (void *)map_library(fd, app);
1176 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1182 app->name = argv[0];
1183 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
1184 /* Find the name that would have been used for the dynamic
1185 * linker had ldd not taken its place. */
1187 for (i=0; i<app->phnum; i++) {
1188 if (app->phdr[i].p_type == PT_INTERP)
1189 lib->name = (void *)(app->base
1190 + app->phdr[i].p_vaddr);
1192 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1195 if (app->tls_size) {
1196 app->tls_id = tls_cnt = 1;
1198 app->tls_offset = 0;
1199 tls_offset = app->tls_size
1200 + ( -((uintptr_t)app->tls_image + app->tls_size)
1201 & (app->tls_align-1) );
1203 tls_offset = app->tls_offset = app->tls_size
1204 + ( -((uintptr_t)app->tls_image + app->tls_size)
1205 & (app->tls_align-1) );
1207 tls_align = MAXP2(tls_align, app->tls_align);
1212 /* Attach to vdso, if provided by the kernel */
1213 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1214 ehdr = (void *)vdso_base;
1215 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1216 vdso->phnum = ehdr->e_phnum;
1217 vdso->phentsize = ehdr->e_phentsize;
1218 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1219 if (phdr->p_type == PT_DYNAMIC)
1220 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1221 if (phdr->p_type == PT_LOAD)
1222 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1225 vdso->shortname = "linux-gate.so.1";
1232 /* Initial dso chain consists only of the app. We temporarily
1233 * append the dynamic linker/libc so we can relocate it, then
1234 * restore the initial chain in preparation for loading third
1235 * party libraries (preload/needed). */
1242 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1244 /* Donate unused parts of app and library mapping to malloc */
1248 /* Load preload/needed libraries, add their symbols to the global
1249 * namespace, and perform all remaining relocations. The main
1250 * program must be relocated LAST since it may contain copy
1251 * relocations which depend on libraries' relocations. */
1252 if (env_preload) load_preload(env_preload);
1256 #ifndef DYNAMIC_IS_RO
1257 for (i=0; app->dynv[i]; i+=2)
1258 if (app->dynv[i]==DT_DEBUG)
1259 app->dynv[i+1] = (size_t)&debug;
1262 reloc_all(app->next);
1266 if (libc.tls_size > sizeof builtin_tls) {
1267 initial_tls = calloc(libc.tls_size, 1);
1269 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1270 argv[0], libc.tls_size);
1274 initial_tls = builtin_tls;
1276 if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) {
1277 dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]);
1281 if (ldso_fail) _exit(127);
1282 if (ldd_mode) _exit(0);
1284 /* Switch to runtime mode: any further failures in the dynamic
1285 * linker are a reportable failure rather than a fatal startup
1286 * error. If the dynamic loader (dlopen) will not be used, free
1287 * all memory used by the dynamic linker. */
1291 debug.bp = _dl_debug_state;
1293 debug.base = lib->base;
1297 __init_libc(envp, argv[0]);
1302 return (void *)aux[AT_ENTRY];
1305 void *dlopen(const char *file, int mode)
1307 struct dso *volatile p, *orig_tail, *next;
1308 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1313 if (!file) return head;
1315 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1316 pthread_rwlock_wrlock(&lock);
1320 orig_tls_cnt = tls_cnt;
1321 orig_tls_offset = tls_offset;
1322 orig_tls_align = tls_align;
1324 noload = mode & RTLD_NOLOAD;
1327 if (setjmp(*rtld_fail)) {
1328 /* Clean up anything new that was (partially) loaded */
1329 if (p && p->deps) for (i=0; p->deps[i]; i++)
1330 if (p->deps[i]->global < 0)
1331 p->deps[i]->global = 0;
1332 for (p=orig_tail->next; p; p=next) {
1334 munmap(p->map, p->map_len);
1338 tls_cnt = orig_tls_cnt;
1339 tls_offset = orig_tls_offset;
1340 tls_align = orig_tls_align;
1346 } else p = load_library(file, head);
1349 snprintf(errbuf, sizeof errbuf, noload ?
1350 "Library %s is not already loaded" :
1351 "Error loading shared library %s: %m",
1357 /* First load handling */
1360 if (p->deps) for (i=0; p->deps[i]; i++)
1361 if (!p->deps[i]->global)
1362 p->deps[i]->global = -1;
1363 if (!p->global) p->global = -1;
1365 if (p->deps) for (i=0; p->deps[i]; i++)
1366 if (p->deps[i]->global < 0)
1367 p->deps[i]->global = 0;
1368 if (p->global < 0) p->global = 0;
1371 if (mode & RTLD_GLOBAL) {
1372 if (p->deps) for (i=0; p->deps[i]; i++)
1373 p->deps[i]->global = 1;
1383 pthread_rwlock_unlock(&lock);
1384 if (p) do_init_fini(orig_tail);
1385 pthread_setcancelstate(cs, 0);
1389 static int invalid_dso_handle(void *h)
1392 for (p=head; p; p=p->next) if (h==p) return 0;
1393 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1398 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1401 uint32_t h = 0, gh = 0;
1403 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1404 if (p == RTLD_DEFAULT) {
1406 } else if (p == RTLD_NEXT) {
1407 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1411 struct symdef def = find_sym(p, s, 0);
1412 if (!def.sym) goto failed;
1413 if ((def.sym->st_info&0xf) == STT_TLS)
1414 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1415 return def.dso->base + def.sym->st_value;
1417 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1421 sym = gnu_lookup(s, gh, p);
1424 sym = sysv_lookup(s, h, p);
1426 if (sym && (sym->st_info&0xf) == STT_TLS)
1427 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1428 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1429 return p->base + sym->st_value;
1430 if (p->deps) for (i=0; p->deps[i]; i++) {
1431 if (p->deps[i]->ghashtab) {
1432 if (!gh) gh = gnu_hash(s);
1433 sym = gnu_lookup(s, gh, p->deps[i]);
1435 if (!h) h = sysv_hash(s);
1436 sym = sysv_lookup(s, h, p->deps[i]);
1438 if (sym && (sym->st_info&0xf) == STT_TLS)
1439 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1440 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1441 return p->deps[i]->base + sym->st_value;
1445 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1449 int __dladdr(const void *addr, Dl_info *info)
1459 pthread_rwlock_rdlock(&lock);
1460 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1461 pthread_rwlock_unlock(&lock);
1466 strings = p->strings;
1468 nsym = p->hashtab[1];
1472 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1473 sym += p->ghashtab[1];
1474 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1475 if (buckets[i] > nsym)
1479 nsym -= p->ghashtab[1];
1480 hashval = buckets + p->ghashtab[0] + nsym;
1482 while (!(*hashval++ & 1));
1486 for (; nsym; nsym--, sym++) {
1488 && (1<<(sym->st_info&0xf) & OK_TYPES)
1489 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1490 void *symaddr = p->base + sym->st_value;
1491 if (symaddr > addr || symaddr < best)
1494 bestname = strings + sym->st_name;
1495 if (addr == symaddr)
1500 if (!best) return 0;
1502 info->dli_fname = p->name;
1503 info->dli_fbase = p->base;
1504 info->dli_sname = bestname;
1505 info->dli_saddr = best;
1510 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1513 pthread_rwlock_rdlock(&lock);
1514 res = do_dlsym(p, s, ra);
1515 pthread_rwlock_unlock(&lock);
1519 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1521 struct dso *current;
1522 struct dl_phdr_info info;
1524 for(current = head; current;) {
1525 info.dlpi_addr = (uintptr_t)current->base;
1526 info.dlpi_name = current->name;
1527 info.dlpi_phdr = current->phdr;
1528 info.dlpi_phnum = current->phnum;
1529 info.dlpi_adds = gencnt;
1531 info.dlpi_tls_modid = current->tls_id;
1532 info.dlpi_tls_data = current->tls_image;
1534 ret = (callback)(&info, sizeof (info), data);
1536 if (ret != 0) break;
1538 pthread_rwlock_rdlock(&lock);
1539 current = current->next;
1540 pthread_rwlock_unlock(&lock);
1545 static int invalid_dso_handle(void *h)
1547 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1551 void *dlopen(const char *file, int mode)
1555 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1559 int __dladdr (const void *addr, Dl_info *info)
1565 int __dlinfo(void *dso, int req, void *res)
1567 if (invalid_dso_handle(dso)) return -1;
1568 if (req != RTLD_DI_LINKMAP) {
1569 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1573 *(struct link_map **)res = dso;
1579 if (!errflag) return 0;
1584 int dlclose(void *p)
1586 return invalid_dso_handle(p);