20 #include <semaphore.h>
21 #include <sys/membarrier.h>
22 #include "pthread_impl.h"
25 #include "malloc_impl.h"
27 static void error(const char *, ...);
29 #define MAXP2(a,b) (-(-(a)&-(b)))
30 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
32 #define container_of(p,t,m) ((t*)((char *)(p)-offsetof(t,m)))
44 struct td_index *next;
49 struct fdpic_loadmap *loadmap;
55 struct dso *next, *prev;
65 struct dso *syms_next, *lazy_next;
66 size_t *lazy, lazy_cnt;
77 struct dso **deps, *needed_by;
79 char *rpath_orig, *rpath;
80 struct tls_module tls;
82 size_t relro_start, relro_end;
84 unsigned char *new_tls;
85 volatile int new_dtv_idx, new_tls_idx;
86 struct td_index *td_index;
87 struct dso *fini_next;
92 struct fdpic_loadmap *loadmap;
107 static struct builtin_tls {
112 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
114 #define ADDEND_LIMIT 4096
115 static size_t *saved_addends, *apply_addends_to;
117 static struct dso ldso;
118 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
119 static char *env_path, *sys_path;
120 static unsigned long long gencnt;
123 static int ldso_fail;
125 static jmp_buf *rtld_fail;
126 static pthread_rwlock_t lock;
127 static struct debug debug;
128 static struct tls_module *tls_tail;
129 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
130 static size_t static_tls_cnt;
131 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
132 static struct fdpic_loadmap *app_loadmap;
133 static struct fdpic_dummy_loadmap app_dummy_loadmap;
135 struct debug *_dl_debug_addr = &debug;
137 extern hidden int __malloc_replaced;
139 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
141 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
143 weak_alias(__init_array_start, __init_array_end);
144 weak_alias(__fini_array_start, __fini_array_end);
146 static int dl_strcmp(const char *l, const char *r)
148 for (; *l==*r && *l; l++, r++);
149 return *(unsigned char *)l - *(unsigned char *)r;
151 #define strcmp(l,r) dl_strcmp(l,r)
153 /* Compute load address for a virtual address in a given dso. */
155 static void *laddr(const struct dso *p, size_t v)
158 if (!p->loadmap) return p->base + v;
159 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
160 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
162 static void *laddr_pg(const struct dso *p, size_t v)
165 size_t pgsz = PAGE_SIZE;
166 if (!p->loadmap) return p->base + v;
168 size_t a = p->loadmap->segs[j].p_vaddr;
169 size_t b = a + p->loadmap->segs[j].p_memsz;
175 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
177 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
178 laddr(p, v), (p)->got })
180 #define laddr(p, v) (void *)((p)->base + (v))
181 #define laddr_pg(p, v) laddr(p, v)
182 #define fpaddr(p, v) ((void (*)())laddr(p, v))
185 static void decode_vec(size_t *v, size_t *a, size_t cnt)
188 for (i=0; i<cnt; i++) a[i] = 0;
189 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
195 static int search_vec(size_t *v, size_t *r, size_t key)
197 for (; v[0]!=key; v+=2)
203 static uint32_t sysv_hash(const char *s0)
205 const unsigned char *s = (void *)s0;
211 return h & 0xfffffff;
214 static uint32_t gnu_hash(const char *s0)
216 const unsigned char *s = (void *)s0;
217 uint_fast32_t h = 5381;
223 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
226 Sym *syms = dso->syms;
227 Elf_Symndx *hashtab = dso->hashtab;
228 char *strings = dso->strings;
229 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
230 if ((!dso->versym || dso->versym[i] >= 0)
231 && (!strcmp(s, strings+syms[i].st_name)))
237 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
239 uint32_t nbuckets = hashtab[0];
240 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
241 uint32_t i = buckets[h1 % nbuckets];
245 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
247 for (h1 |= 1; ; i++) {
248 uint32_t h2 = *hashval++;
249 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
250 && !strcmp(s, dso->strings + dso->syms[i].st_name))
258 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
260 const size_t *bloomwords = (const void *)(hashtab+4);
261 size_t f = bloomwords[fofs & (hashtab[2]-1)];
262 if (!(f & fmask)) return 0;
264 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
265 if (!(f & 1)) return 0;
267 return gnu_lookup(h1, hashtab, dso, s);
270 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
271 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
273 #ifndef ARCH_SYM_REJECT_UND
274 #define ARCH_SYM_REJECT_UND(s) 0
277 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
279 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
280 size_t ghm = 1ul << gh % (8*sizeof(size_t));
281 struct symdef def = {0};
282 for (; dso; dso=dso->syms_next) {
284 if ((ght = dso->ghashtab)) {
285 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
287 if (!h) h = sysv_hash(s);
288 sym = sysv_lookup(s, h, dso);
292 if (need_def || (sym->st_info&0xf) == STT_TLS
293 || ARCH_SYM_REJECT_UND(sym))
296 if ((sym->st_info&0xf) != STT_TLS)
298 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
299 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
307 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
309 unsigned char *base = dso->base;
310 Sym *syms = dso->syms;
311 char *strings = dso->strings;
322 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
325 /* Only ldso's REL table needs addend saving/reuse. */
326 if (rel == apply_addends_to)
331 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
332 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
333 type = R_TYPE(rel[1]);
334 if (type == REL_NONE) continue;
335 reloc_addr = laddr(dso, rel[0]);
339 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
341 } else if (reuse_addends) {
342 /* Save original addend in stage 2 where the dso
343 * chain consists of just ldso; otherwise read back
344 * saved addend since the inline one was clobbered. */
346 saved_addends[save_slot] = *reloc_addr;
347 addend = saved_addends[save_slot++];
349 addend = *reloc_addr;
352 sym_index = R_SYM(rel[1]);
354 sym = syms + sym_index;
355 name = strings + sym->st_name;
356 ctx = type==REL_COPY ? head->syms_next : head;
357 def = (sym->st_info&0xf) == STT_SECTION
358 ? (struct symdef){ .dso = dso, .sym = sym }
359 : find_sym(ctx, name, type==REL_PLT);
360 if (!def.sym && (sym->st_shndx != SHN_UNDEF
361 || sym->st_info>>4 != STB_WEAK)) {
362 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
363 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
364 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
365 dso->lazy[3*dso->lazy_cnt+2] = addend;
369 error("Error relocating %s: %s: symbol not found",
371 if (runtime) longjmp(*rtld_fail, 1);
380 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
381 tls_val = def.sym ? def.sym->st_value : 0;
383 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
384 && runtime && def.dso->tls_id > static_tls_cnt) {
385 error("Error relocating %s: %s: initial-exec TLS "
386 "resolves to dynamic definition in %s",
387 dso->name, name, def.dso->name);
388 longjmp(*rtld_fail, 1);
395 addend -= (size_t)reloc_addr;
399 *reloc_addr = sym_val + addend;
402 *reloc_addr = (size_t)base + addend;
405 if (sym) *reloc_addr = sym_val + addend;
406 else *reloc_addr = (size_t)base + addend;
409 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
412 *(uint32_t *)reloc_addr = sym_val + addend
413 - (size_t)reloc_addr;
416 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
417 + (def.sym - def.dso->syms)) : 0;
419 case REL_FUNCDESC_VAL:
420 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
421 else *reloc_addr = sym_val;
422 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
425 *reloc_addr = def.dso->tls_id;
428 *reloc_addr = tls_val + addend - DTP_OFFSET;
432 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
436 *reloc_addr = tls_val - def.dso->tls.offset + addend;
439 *reloc_addr = def.dso->tls.offset - tls_val + addend;
443 if (stride<3) addend = reloc_addr[1];
444 if (runtime && def.dso->tls_id > static_tls_cnt) {
445 struct td_index *new = malloc(sizeof *new);
448 "Error relocating %s: cannot allocate TLSDESC for %s",
449 dso->name, sym ? name : "(local)" );
450 longjmp(*rtld_fail, 1);
452 new->next = dso->td_index;
454 new->args[0] = def.dso->tls_id;
455 new->args[1] = tls_val + addend - DTP_OFFSET;
456 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
457 reloc_addr[1] = (size_t)new;
459 reloc_addr[0] = (size_t)__tlsdesc_static;
461 reloc_addr[1] = tls_val + def.dso->tls.offset
464 reloc_addr[1] = tls_val - def.dso->tls.offset
468 #ifdef TLSDESC_BACKWARDS
469 /* Some archs (32-bit ARM at least) invert the order of
470 * the descriptor members. Fix them up here. */
471 size_t tmp = reloc_addr[0];
472 reloc_addr[0] = reloc_addr[1];
477 error("Error relocating %s: unsupported relocation type %d",
479 if (runtime) longjmp(*rtld_fail, 1);
485 static void redo_lazy_relocs()
487 struct dso *p = lazy_head, *next;
491 size_t size = p->lazy_cnt*3*sizeof(size_t);
493 do_relocs(p, p->lazy, size, 3);
495 p->lazy_next = lazy_head;
505 /* A huge hack: to make up for the wastefulness of shared libraries
506 * needing at least a page of dirty memory even if they have no global
507 * data, we reclaim the gaps at the beginning and end of writable maps
508 * and "donate" them to the heap. */
510 static void reclaim(struct dso *dso, size_t start, size_t end)
512 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
513 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
514 if (start >= end) return;
515 char *base = laddr_pg(dso, start);
516 __malloc_donate(base, base+(end-start));
519 static void reclaim_gaps(struct dso *dso)
521 Phdr *ph = dso->phdr;
522 size_t phcnt = dso->phnum;
524 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
525 if (ph->p_type!=PT_LOAD) continue;
526 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
527 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
528 reclaim(dso, ph->p_vaddr+ph->p_memsz,
529 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
533 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
535 static int no_map_fixed;
538 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
539 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
543 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
544 if (flags & MAP_ANONYMOUS) {
549 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
550 for (q=p; n; q+=r, off+=r, n-=r) {
552 if (r < 0 && errno != EINTR) return MAP_FAILED;
561 static void unmap_library(struct dso *dso)
565 for (i=0; i<dso->loadmap->nsegs; i++) {
566 if (!dso->loadmap->segs[i].p_memsz)
568 munmap((void *)dso->loadmap->segs[i].addr,
569 dso->loadmap->segs[i].p_memsz);
572 } else if (dso->map && dso->map_len) {
573 munmap(dso->map, dso->map_len);
577 static void *map_library(int fd, struct dso *dso)
579 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
580 void *allocated_buf=0;
582 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
583 size_t this_min, this_max;
589 unsigned char *map=MAP_FAILED, *base;
594 ssize_t l = read(fd, buf, sizeof buf);
597 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
599 phsize = eh->e_phentsize * eh->e_phnum;
600 if (phsize > sizeof buf - sizeof *eh) {
601 allocated_buf = malloc(phsize);
602 if (!allocated_buf) return 0;
603 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
604 if (l < 0) goto error;
605 if (l != phsize) goto noexec;
606 ph = ph0 = allocated_buf;
607 } else if (eh->e_phoff + phsize > l) {
608 l = pread(fd, buf+1, phsize, eh->e_phoff);
609 if (l < 0) goto error;
610 if (l != phsize) goto noexec;
611 ph = ph0 = (void *)(buf + 1);
613 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
615 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
616 if (ph->p_type == PT_DYNAMIC) {
618 } else if (ph->p_type == PT_TLS) {
619 tls_image = ph->p_vaddr;
620 dso->tls.align = ph->p_align;
621 dso->tls.len = ph->p_filesz;
622 dso->tls.size = ph->p_memsz;
623 } else if (ph->p_type == PT_GNU_RELRO) {
624 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
625 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
626 } else if (ph->p_type == PT_GNU_STACK) {
627 if (!runtime && ph->p_memsz > __default_stacksize) {
628 __default_stacksize =
629 ph->p_memsz < DEFAULT_STACK_MAX ?
630 ph->p_memsz : DEFAULT_STACK_MAX;
633 if (ph->p_type != PT_LOAD) continue;
635 if (ph->p_vaddr < addr_min) {
636 addr_min = ph->p_vaddr;
637 off_start = ph->p_offset;
638 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
639 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
640 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
642 if (ph->p_vaddr+ph->p_memsz > addr_max) {
643 addr_max = ph->p_vaddr+ph->p_memsz;
646 if (!dyn) goto noexec;
647 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
648 dso->loadmap = calloc(1, sizeof *dso->loadmap
649 + nsegs * sizeof *dso->loadmap->segs);
650 if (!dso->loadmap) goto error;
651 dso->loadmap->nsegs = nsegs;
652 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
653 if (ph->p_type != PT_LOAD) continue;
654 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
655 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
656 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
657 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
659 fd, ph->p_offset & -PAGE_SIZE);
660 if (map == MAP_FAILED) {
664 dso->loadmap->segs[i].addr = (size_t)map +
665 (ph->p_vaddr & PAGE_SIZE-1);
666 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
667 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
669 if (prot & PROT_WRITE) {
670 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
672 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
673 size_t pgend = brk + ph->p_memsz - ph->p_filesz
674 + PAGE_SIZE-1 & -PAGE_SIZE;
675 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
677 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
678 -1, off_start) == MAP_FAILED)
680 memset(map + brk, 0, pgbrk-brk);
683 map = (void *)dso->loadmap->segs[0].addr;
687 addr_max += PAGE_SIZE-1;
688 addr_max &= -PAGE_SIZE;
689 addr_min &= -PAGE_SIZE;
690 off_start &= -PAGE_SIZE;
691 map_len = addr_max - addr_min + off_start;
692 /* The first time, we map too much, possibly even more than
693 * the length of the file. This is okay because we will not
694 * use the invalid part; we just need to reserve the right
695 * amount of virtual address space to map over later. */
696 map = DL_NOMMU_SUPPORT
697 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
698 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
699 : mmap((void *)addr_min, map_len, prot,
700 MAP_PRIVATE, fd, off_start);
701 if (map==MAP_FAILED) goto error;
703 dso->map_len = map_len;
704 /* If the loaded file is not relocatable and the requested address is
705 * not available, then the load operation must fail. */
706 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
710 base = map - addr_min;
713 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
714 if (ph->p_type != PT_LOAD) continue;
715 /* Check if the programs headers are in this load segment, and
716 * if so, record the address for use by dl_iterate_phdr. */
717 if (!dso->phdr && eh->e_phoff >= ph->p_offset
718 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
719 dso->phdr = (void *)(base + ph->p_vaddr
720 + (eh->e_phoff-ph->p_offset));
721 dso->phnum = eh->e_phnum;
722 dso->phentsize = eh->e_phentsize;
724 this_min = ph->p_vaddr & -PAGE_SIZE;
725 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
726 off_start = ph->p_offset & -PAGE_SIZE;
727 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
728 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
729 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
730 /* Reuse the existing mapping for the lowest-address LOAD */
731 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
732 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
734 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
735 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
736 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
737 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
738 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)
742 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
743 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
744 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
751 dso->dynv = laddr(dso, dyn);
752 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
758 if (map!=MAP_FAILED) unmap_library(dso);
763 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
768 s += strspn(s, ":\n");
769 l = strcspn(s, ":\n");
770 if (l-1 >= INT_MAX) return -1;
771 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
772 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
780 /* Any negative value but -1 will inhibit
781 * futher path search. */
789 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
792 const char *s, *t, *origin;
794 if (p->rpath || !p->rpath_orig) return 0;
795 if (!strchr(p->rpath_orig, '$')) {
796 p->rpath = p->rpath_orig;
801 while ((t=strchr(s, '$'))) {
802 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
807 if (n > SSIZE_MAX/PATH_MAX) return 0;
809 if (p->kernel_mapped) {
810 /* $ORIGIN searches cannot be performed for the main program
811 * when it is suid/sgid/AT_SECURE. This is because the
812 * pathname is under the control of the caller of execve.
813 * For libraries, however, $ORIGIN can be processed safely
814 * since the library's pathname came from a trusted source
815 * (either system paths or a call to dlopen). */
818 l = readlink("/proc/self/exe", buf, buf_size);
819 if (l == -1) switch (errno) {
834 t = strrchr(origin, '/');
838 /* Normally p->name will always be an absolute or relative
839 * pathname containing at least one '/' character, but in the
840 * case where ldso was invoked as a command to execute a
841 * program in the working directory, app.name may not. Fix. */
845 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
846 if (libc.secure && *origin != '/')
848 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
849 if (!p->rpath) return -1;
853 while ((t=strchr(s, '$'))) {
856 memcpy(d, origin, l);
858 /* It was determined previously that the '$' is followed
859 * either by "ORIGIN" or "{ORIGIN}". */
860 s = t + 7 + 2*(t[1]=='{');
866 static void decode_dyn(struct dso *p)
869 decode_vec(p->dynv, dyn, DYN_CNT);
870 p->syms = laddr(p, dyn[DT_SYMTAB]);
871 p->strings = laddr(p, dyn[DT_STRTAB]);
872 if (dyn[0]&(1<<DT_HASH))
873 p->hashtab = laddr(p, dyn[DT_HASH]);
874 if (dyn[0]&(1<<DT_RPATH))
875 p->rpath_orig = p->strings + dyn[DT_RPATH];
876 if (dyn[0]&(1<<DT_RUNPATH))
877 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
878 if (dyn[0]&(1<<DT_PLTGOT))
879 p->got = laddr(p, dyn[DT_PLTGOT]);
880 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
881 p->ghashtab = laddr(p, *dyn);
882 if (search_vec(p->dynv, dyn, DT_VERSYM))
883 p->versym = laddr(p, *dyn);
886 static size_t count_syms(struct dso *p)
888 if (p->hashtab) return p->hashtab[1];
891 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
893 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
894 if (buckets[i] > nsym)
898 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
900 while (!(*hashval++ & 1));
905 static void *dl_mmap(size_t n)
908 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
910 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
912 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
914 return p == MAP_FAILED ? 0 : p;
917 static void makefuncdescs(struct dso *p)
919 static int self_done;
920 size_t nsym = count_syms(p);
921 size_t i, size = nsym * sizeof(*p->funcdescs);
924 p->funcdescs = dl_mmap(size);
927 p->funcdescs = malloc(size);
930 if (!runtime) a_crash();
931 error("Error allocating function descriptors for %s", p->name);
932 longjmp(*rtld_fail, 1);
934 for (i=0; i<nsym; i++) {
935 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
936 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
937 p->funcdescs[i].got = p->got;
939 p->funcdescs[i].addr = 0;
940 p->funcdescs[i].got = 0;
945 static struct dso *load_library(const char *name, struct dso *needed_by)
947 char buf[2*NAME_MAX+2];
948 const char *pathname;
950 struct dso *p, temp_dso = {0};
962 /* Catch and block attempts to reload the implementation itself */
963 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
964 static const char reserved[] =
965 "c.pthread.rt.m.dl.util.xnet.";
966 const char *rp, *next;
967 for (rp=reserved; *rp; rp=next) {
968 next = strchr(rp, '.') + 1;
969 if (strncmp(name+3, rp, next-rp) == 0)
974 /* Track which names have been resolved
975 * and only report each one once. */
976 static unsigned reported;
977 unsigned mask = 1U<<(rp-reserved);
978 if (!(reported & mask)) {
980 dprintf(1, "\t%s => %s (%p)\n",
988 if (!strcmp(name, ldso.name)) is_self = 1;
997 if (strchr(name, '/')) {
999 fd = open(name, O_RDONLY|O_CLOEXEC);
1001 /* Search for the name to see if it's already loaded */
1002 for (p=head->next; p; p=p->next) {
1003 if (p->shortname && !strcmp(p->shortname, name)) {
1007 if (strlen(name) > NAME_MAX) return 0;
1009 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1010 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1011 if (fixup_rpath(p, buf, sizeof buf) < 0)
1012 fd = -2; /* Inhibit further search. */
1014 fd = path_open(name, p->rpath, buf, sizeof buf);
1020 if (ldso.name[0]=='/') {
1022 for (s=t=z=ldso.name; *s; s++)
1023 if (*s=='/') z=t, t=s;
1024 prefix_len = z-ldso.name;
1025 if (prefix_len < PATH_MAX)
1032 char etc_ldso_path[prefix_len + 1
1033 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1034 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1035 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1036 (int)prefix_len, prefix);
1037 FILE *f = fopen(etc_ldso_path, "rbe");
1039 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1044 } else if (errno != ENOENT) {
1048 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1049 fd = path_open(name, sys_path, buf, sizeof buf);
1053 if (fd < 0) return 0;
1054 if (fstat(fd, &st) < 0) {
1058 for (p=head->next; p; p=p->next) {
1059 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1060 /* If this library was previously loaded with a
1061 * pathname but a search found the same inode,
1062 * setup its shortname so it can be found by name. */
1063 if (!p->shortname && pathname != name)
1064 p->shortname = strrchr(p->name, '/')+1;
1069 map = noload ? 0 : map_library(fd, &temp_dso);
1073 /* Avoid the danger of getting two versions of libc mapped into the
1074 * same process when an absolute pathname was used. The symbols
1075 * checked are chosen to catch both musl and glibc, and to avoid
1076 * false positives from interposition-hack libraries. */
1077 decode_dyn(&temp_dso);
1078 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1079 find_sym(&temp_dso, "stdin", 1).sym) {
1080 unmap_library(&temp_dso);
1081 return load_library("libc.so", needed_by);
1083 /* Past this point, if we haven't reached runtime yet, ldso has
1084 * committed either to use the mapped library or to abort execution.
1085 * Unmapping is not possible, so we can safely reclaim gaps. */
1086 if (!runtime) reclaim_gaps(&temp_dso);
1088 /* Allocate storage for the new DSO. When there is TLS, this
1089 * storage must include a reservation for all pre-existing
1090 * threads to obtain copies of both the new TLS, and an
1091 * extended DTV capable of storing an additional slot for
1092 * the newly-loaded DSO. */
1093 alloc_size = sizeof *p + strlen(pathname) + 1;
1094 if (runtime && temp_dso.tls.image) {
1095 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1096 + sizeof(void *) * (tls_cnt+3);
1097 n_th = libc.threads_minus_1 + 1;
1098 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1099 else alloc_size += n_th * per_th;
1101 p = calloc(1, alloc_size);
1103 unmap_library(&temp_dso);
1106 memcpy(p, &temp_dso, sizeof temp_dso);
1109 p->needed_by = needed_by;
1111 p->runtime_loaded = runtime;
1112 strcpy(p->name, pathname);
1113 /* Add a shortname only if name arg was not an explicit pathname. */
1114 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1116 p->tls_id = ++tls_cnt;
1117 tls_align = MAXP2(tls_align, p->tls.align);
1119 p->tls.offset = tls_offset + ( (tls_align-1) &
1120 -(tls_offset + (uintptr_t)p->tls.image) );
1121 tls_offset += p->tls.size;
1123 tls_offset += p->tls.size + p->tls.align - 1;
1124 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1126 p->tls.offset = tls_offset;
1128 p->new_dtv = (void *)(-sizeof(size_t) &
1129 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1130 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1131 if (tls_tail) tls_tail->next = &p->tls;
1132 else libc.tls_head = &p->tls;
1140 if (DL_FDPIC) makefuncdescs(p);
1142 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1147 static void load_direct_deps(struct dso *p)
1150 if (p->deps) return;
1151 /* For head, all preloads are direct pseudo-dependencies.
1152 * Count and include them now to avoid realloc later. */
1153 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1155 for (i=0; p->dynv[i]; i+=2)
1156 if (p->dynv[i] == DT_NEEDED) cnt++;
1157 p->deps = calloc(cnt+1, sizeof *p->deps);
1159 error("Error loading dependencies for %s", p->name);
1160 if (runtime) longjmp(*rtld_fail, 1);
1163 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1165 for (i=0; p->dynv[i]; i+=2) {
1166 if (p->dynv[i] != DT_NEEDED) continue;
1167 struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
1169 error("Error loading shared library %s: %m (needed by %s)",
1170 p->strings + p->dynv[i+1], p->name);
1171 if (runtime) longjmp(*rtld_fail, 1);
1174 p->deps[cnt++] = dep;
1177 p->ndeps_direct = cnt;
1180 static void load_deps(struct dso *p)
1182 if (p->deps) return;
1183 for (; p; p=p->next)
1184 load_direct_deps(p);
1187 static void extend_bfs_deps(struct dso *p)
1189 size_t i, j, cnt, ndeps_all;
1192 /* Can't use realloc if the original p->deps was allocated at
1193 * program entry and malloc has been replaced. */
1194 int no_realloc = __malloc_replaced && !p->runtime_loaded;
1196 if (p->bfs_built) return;
1197 ndeps_all = p->ndeps_direct;
1199 /* Mark existing (direct) deps so they won't be duplicated. */
1200 for (i=0; p->deps[i]; i++)
1201 p->deps[i]->mark = 1;
1203 /* For each dependency already in the list, copy its list of direct
1204 * dependencies to the list, excluding any items already in the
1205 * list. Note that the list this loop iterates over will grow during
1206 * the loop, but since duplicates are excluded, growth is bounded. */
1207 for (i=0; p->deps[i]; i++) {
1208 struct dso *dep = p->deps[i];
1209 for (j=cnt=0; j<dep->ndeps_direct; j++)
1210 if (!dep->deps[j]->mark) cnt++;
1212 malloc(sizeof(*tmp) * (ndeps_all+cnt+1)) :
1213 realloc(p->deps, sizeof(*tmp) * (ndeps_all+cnt+1));
1215 error("Error recording dependencies for %s", p->name);
1216 if (runtime) longjmp(*rtld_fail, 1);
1220 memcpy(tmp, p->deps, sizeof(*tmp) * (ndeps_all+1));
1224 for (j=0; j<dep->ndeps_direct; j++) {
1225 if (dep->deps[j]->mark) continue;
1226 dep->deps[j]->mark = 1;
1227 p->deps[ndeps_all++] = dep->deps[j];
1229 p->deps[ndeps_all] = 0;
1232 for (p=head; p; p=p->next)
1236 static void load_preload(char *s)
1240 for (z=s; *z; s=z) {
1241 for ( ; *s && (isspace(*s) || *s==':'); s++);
1242 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1250 static void add_syms(struct dso *p)
1252 if (!p->syms_next && syms_tail != p) {
1253 syms_tail->syms_next = p;
1258 static void revert_syms(struct dso *old_tail)
1260 struct dso *p, *next;
1261 /* Chop off the tail of the list of dsos that participate in
1262 * the global symbol table, reverting them to RTLD_LOCAL. */
1263 for (p=old_tail; p; p=next) {
1264 next = p->syms_next;
1267 syms_tail = old_tail;
1270 static void do_mips_relocs(struct dso *p, size_t *got)
1272 size_t i, j, rel[2];
1273 unsigned char *base = p->base;
1274 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1278 while (i--) *got++ += (size_t)base;
1280 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1281 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1282 Sym *sym = p->syms + j;
1283 rel[0] = (unsigned char *)got - base;
1284 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1285 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1286 do_relocs(p, rel, sizeof rel, 2);
1290 static void reloc_all(struct dso *p)
1292 size_t dyn[DYN_CNT];
1293 for (; p; p=p->next) {
1294 if (p->relocated) continue;
1295 decode_vec(p->dynv, dyn, DYN_CNT);
1296 if (NEED_MIPS_GOT_RELOCS)
1297 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1298 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1299 2+(dyn[DT_PLTREL]==DT_RELA));
1300 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1301 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1303 if (head != &ldso && p->relro_start != p->relro_end &&
1304 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1305 && errno != ENOSYS) {
1306 error("Error relocating %s: RELRO protection failed: %m",
1308 if (runtime) longjmp(*rtld_fail, 1);
1315 static void kernel_mapped_dso(struct dso *p)
1317 size_t min_addr = -1, max_addr = 0, cnt;
1319 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1320 if (ph->p_type == PT_DYNAMIC) {
1321 p->dynv = laddr(p, ph->p_vaddr);
1322 } else if (ph->p_type == PT_GNU_RELRO) {
1323 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1324 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1325 } else if (ph->p_type == PT_GNU_STACK) {
1326 if (!runtime && ph->p_memsz > __default_stacksize) {
1327 __default_stacksize =
1328 ph->p_memsz < DEFAULT_STACK_MAX ?
1329 ph->p_memsz : DEFAULT_STACK_MAX;
1332 if (ph->p_type != PT_LOAD) continue;
1333 if (ph->p_vaddr < min_addr)
1334 min_addr = ph->p_vaddr;
1335 if (ph->p_vaddr+ph->p_memsz > max_addr)
1336 max_addr = ph->p_vaddr+ph->p_memsz;
1338 min_addr &= -PAGE_SIZE;
1339 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1340 p->map = p->base + min_addr;
1341 p->map_len = max_addr - min_addr;
1342 p->kernel_mapped = 1;
1345 void __libc_exit_fini()
1348 size_t dyn[DYN_CNT];
1349 for (p=fini_head; p; p=p->fini_next) {
1350 if (!p->constructed) continue;
1351 decode_vec(p->dynv, dyn, DYN_CNT);
1352 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1353 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1354 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1355 while (n--) ((void (*)(void))*--fn)();
1357 #ifndef NO_LEGACY_INITFINI
1358 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1359 fpaddr(p, dyn[DT_FINI])();
1364 static void do_init_fini(struct dso *p)
1366 size_t dyn[DYN_CNT];
1367 int need_locking = libc.threads_minus_1;
1368 /* Allow recursive calls that arise when a library calls
1369 * dlopen from one of its constructors, but block any
1370 * other threads until all ctors have finished. */
1371 if (need_locking) pthread_mutex_lock(&init_fini_lock);
1372 for (; p; p=p->prev) {
1373 if (p->constructed) continue;
1375 decode_vec(p->dynv, dyn, DYN_CNT);
1376 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1377 p->fini_next = fini_head;
1380 #ifndef NO_LEGACY_INITFINI
1381 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1382 fpaddr(p, dyn[DT_INIT])();
1384 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1385 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1386 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1387 while (n--) ((void (*)(void))*fn++)();
1389 if (!need_locking && libc.threads_minus_1) {
1391 pthread_mutex_lock(&init_fini_lock);
1394 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1397 void __libc_start_init(void)
1402 static void dl_debug_state(void)
1406 weak_alias(dl_debug_state, _dl_debug_state);
1408 void __init_tls(size_t *auxv)
1412 static void update_tls_size()
1414 libc.tls_cnt = tls_cnt;
1415 libc.tls_align = tls_align;
1416 libc.tls_size = ALIGN(
1417 (1+tls_cnt) * sizeof(void *) +
1419 sizeof(struct pthread) +
1424 static void install_new_tls(void)
1427 pthread_t self = __pthread_self(), td;
1428 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1429 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1432 size_t old_cnt = self->dtv[0];
1434 __block_app_sigs(&set);
1436 /* Copy existing dtv contents from all existing threads. */
1437 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1438 memcpy(newdtv+i, td->dtv,
1439 (old_cnt+1)*sizeof(uintptr_t));
1440 newdtv[i][0] = tls_cnt;
1442 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1443 for (p=head; ; p=p->next) {
1444 if (p->tls_id <= old_cnt) continue;
1445 unsigned char *mem = p->new_tls;
1446 for (j=0; j<i; j++) {
1447 unsigned char *new = mem;
1448 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1450 memcpy(new, p->tls.image, p->tls.len);
1451 newdtv[j][p->tls_id] =
1452 (uintptr_t)new + DTP_OFFSET;
1453 mem += p->tls.size + p->tls.align;
1455 if (p->tls_id == tls_cnt) break;
1458 /* Broadcast barrier to ensure contents of new dtv is visible
1459 * if the new dtv pointer is. The __membarrier function has a
1460 * fallback emulation using signals for kernels that lack the
1461 * feature at the syscall level. */
1463 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1465 /* Install new dtv for each thread. */
1466 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1467 td->dtv = td->dtv_copy = newdtv[j];
1471 __restore_sigs(&set);
1474 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1475 * following stage 2 and stage 3 functions via primitive symbolic lookup
1476 * since it does not have access to their addresses to begin with. */
1478 /* Stage 2 of the dynamic linker is called after relative relocations
1479 * have been processed. It can make function calls to static functions
1480 * and access string literals and static data, but cannot use extern
1481 * symbols. Its job is to perform symbolic relocations on the dynamic
1482 * linker itself, but some of the relocations performed may need to be
1483 * replaced later due to copy relocations in the main program. */
1485 hidden void __dls2(unsigned char *base, size_t *sp)
1488 void *p1 = (void *)sp[-2];
1489 void *p2 = (void *)sp[-1];
1491 size_t *auxv, aux[AUX_CNT];
1492 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1494 decode_vec(auxv, aux, AUX_CNT);
1495 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1496 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1498 app_loadmap = p2 ? p1 : 0;
1499 ldso.loadmap = p2 ? p2 : p1;
1500 ldso.base = laddr(&ldso, 0);
1504 Ehdr *ehdr = (void *)ldso.base;
1505 ldso.name = ldso.shortname = "libc.so";
1506 ldso.phnum = ehdr->e_phnum;
1507 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1508 ldso.phentsize = ehdr->e_phentsize;
1509 kernel_mapped_dso(&ldso);
1512 if (DL_FDPIC) makefuncdescs(&ldso);
1514 /* Prepare storage for to save clobbered REL addends so they
1515 * can be reused in stage 3. There should be very few. If
1516 * something goes wrong and there are a huge number, abort
1517 * instead of risking stack overflow. */
1518 size_t dyn[DYN_CNT];
1519 decode_vec(ldso.dynv, dyn, DYN_CNT);
1520 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1521 size_t rel_size = dyn[DT_RELSZ];
1522 size_t symbolic_rel_cnt = 0;
1523 apply_addends_to = rel;
1524 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1525 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1526 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1527 size_t addends[symbolic_rel_cnt+1];
1528 saved_addends = addends;
1535 /* Call dynamic linker stage-2b, __dls2b, looking it up
1536 * symbolically as a barrier against moving the address
1537 * load across the above relocation processing. */
1538 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1539 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
1540 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
1543 /* Stage 2b sets up a valid thread pointer, which requires relocations
1544 * completed in stage 2, and on which stage 3 is permitted to depend.
1545 * This is done as a separate stage, with symbolic lookup as a barrier,
1546 * so that loads of the thread pointer and &errno can be pure/const and
1547 * thereby hoistable. */
1549 _Noreturn void __dls2b(size_t *sp)
1551 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1552 * use during dynamic linking. If possible it will also serve as the
1553 * thread pointer at runtime. */
1554 libc.tls_size = sizeof builtin_tls;
1555 libc.tls_align = tls_align;
1556 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1560 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1561 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1562 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1565 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1566 * fully functional. Its job is to load (if not already loaded) and
1567 * process dependencies and relocations for the main application and
1568 * transfer control to its entry point. */
1570 _Noreturn void __dls3(size_t *sp)
1572 static struct dso app, vdso;
1573 size_t aux[AUX_CNT], *auxv;
1575 char *env_preload=0;
1576 char *replace_argv0=0;
1579 char **argv = (void *)(sp+1);
1580 char **argv_orig = argv;
1581 char **envp = argv+argc+1;
1583 /* Find aux vector just past environ[] and use it to initialize
1584 * global data that may be needed before we can make syscalls. */
1586 for (i=argc+1; argv[i]; i++);
1587 libc.auxv = auxv = (void *)(argv+i+1);
1588 decode_vec(auxv, aux, AUX_CNT);
1589 __hwcap = aux[AT_HWCAP];
1590 libc.page_size = aux[AT_PAGESZ];
1591 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1592 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1594 /* Only trust user/env if kernel says we're not suid/sgid */
1596 env_path = getenv("LD_LIBRARY_PATH");
1597 env_preload = getenv("LD_PRELOAD");
1600 /* If the main program was already loaded by the kernel,
1601 * AT_PHDR will point to some location other than the dynamic
1602 * linker's program headers. */
1603 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1604 size_t interp_off = 0;
1605 size_t tls_image = 0;
1606 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1607 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1608 app.phnum = aux[AT_PHNUM];
1609 app.phentsize = aux[AT_PHENT];
1610 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1611 if (phdr->p_type == PT_PHDR)
1612 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1613 else if (phdr->p_type == PT_INTERP)
1614 interp_off = (size_t)phdr->p_vaddr;
1615 else if (phdr->p_type == PT_TLS) {
1616 tls_image = phdr->p_vaddr;
1617 app.tls.len = phdr->p_filesz;
1618 app.tls.size = phdr->p_memsz;
1619 app.tls.align = phdr->p_align;
1622 if (DL_FDPIC) app.loadmap = app_loadmap;
1623 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1624 if (interp_off) ldso.name = laddr(&app, interp_off);
1625 if ((aux[0] & (1UL<<AT_EXECFN))
1626 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1627 app.name = (char *)aux[AT_EXECFN];
1630 kernel_mapped_dso(&app);
1633 char *ldname = argv[0];
1634 size_t l = strlen(ldname);
1635 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1637 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1638 char *opt = argv[0]+2;
1639 *argv++ = (void *)-1;
1642 } else if (!memcmp(opt, "list", 5)) {
1644 } else if (!memcmp(opt, "library-path", 12)) {
1645 if (opt[12]=='=') env_path = opt+13;
1646 else if (opt[12]) *argv = 0;
1647 else if (*argv) env_path = *argv++;
1648 } else if (!memcmp(opt, "preload", 7)) {
1649 if (opt[7]=='=') env_preload = opt+8;
1650 else if (opt[7]) *argv = 0;
1651 else if (*argv) env_preload = *argv++;
1652 } else if (!memcmp(opt, "argv0", 5)) {
1653 if (opt[5]=='=') replace_argv0 = opt+6;
1654 else if (opt[5]) *argv = 0;
1655 else if (*argv) replace_argv0 = *argv++;
1660 argv[-1] = (void *)(argc - (argv-argv_orig));
1662 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1664 "Dynamic Program Loader\n"
1665 "Usage: %s [options] [--] pathname%s\n",
1666 __libc_version, ldname,
1667 ldd_mode ? "" : " [args]");
1670 fd = open(argv[0], O_RDONLY);
1672 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1675 Ehdr *ehdr = (void *)map_library(fd, &app);
1677 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1683 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1684 /* Find the name that would have been used for the dynamic
1685 * linker had ldd not taken its place. */
1687 for (i=0; i<app.phnum; i++) {
1688 if (app.phdr[i].p_type == PT_INTERP)
1689 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1691 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1695 libc.tls_head = tls_tail = &app.tls;
1696 app.tls_id = tls_cnt = 1;
1698 app.tls.offset = GAP_ABOVE_TP;
1699 app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
1700 tls_offset = app.tls.offset + app.tls.size
1701 + ( -((uintptr_t)app.tls.image + app.tls.size)
1702 & (app.tls.align-1) );
1704 tls_offset = app.tls.offset = app.tls.size
1705 + ( -((uintptr_t)app.tls.image + app.tls.size)
1706 & (app.tls.align-1) );
1708 tls_align = MAXP2(tls_align, app.tls.align);
1712 makefuncdescs(&app);
1714 app.loadmap = (void *)&app_dummy_loadmap;
1715 app.loadmap->nsegs = 1;
1716 app.loadmap->segs[0].addr = (size_t)app.map;
1717 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1719 app.loadmap->segs[0].p_memsz = app.map_len;
1721 argv[-3] = (void *)app.loadmap;
1724 /* Initial dso chain consists only of the app. */
1725 head = tail = syms_tail = &app;
1727 /* Donate unused parts of app and library mapping to malloc */
1729 reclaim_gaps(&ldso);
1731 /* Load preload/needed libraries, add symbols to global namespace. */
1732 if (env_preload) load_preload(env_preload);
1734 for (struct dso *p=head; p; p=p->next)
1737 /* Attach to vdso, if provided by the kernel, last so that it does
1738 * not become part of the global namespace. */
1739 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1740 Ehdr *ehdr = (void *)vdso_base;
1741 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1742 vdso.phnum = ehdr->e_phnum;
1743 vdso.phentsize = ehdr->e_phentsize;
1744 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1745 if (phdr->p_type == PT_DYNAMIC)
1746 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1747 if (phdr->p_type == PT_LOAD)
1748 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1751 vdso.shortname = "linux-gate.so.1";
1759 for (i=0; app.dynv[i]; i+=2) {
1760 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1761 app.dynv[i+1] = (size_t)&debug;
1762 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1763 size_t *ptr = (size_t *) app.dynv[i+1];
1764 *ptr = (size_t)&debug;
1768 /* The main program must be relocated LAST since it may contin
1769 * copy relocations which depend on libraries' relocations. */
1770 reloc_all(app.next);
1774 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1775 void *initial_tls = calloc(libc.tls_size, 1);
1777 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1778 argv[0], libc.tls_size);
1781 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1785 size_t tmp_tls_size = libc.tls_size;
1786 pthread_t self = __pthread_self();
1787 /* Temporarily set the tls size to the full size of
1788 * builtin_tls so that __copy_tls will use the same layout
1789 * as it did for before. Then check, just to be safe. */
1790 libc.tls_size = sizeof builtin_tls;
1791 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1792 libc.tls_size = tmp_tls_size;
1794 static_tls_cnt = tls_cnt;
1796 if (ldso_fail) _exit(127);
1797 if (ldd_mode) _exit(0);
1799 /* Determine if malloc was interposed by a replacement implementation
1800 * so that calloc and the memalign family can harden against the
1801 * possibility of incomplete replacement. */
1802 if (find_sym(head, "malloc", 1).dso != &ldso)
1803 __malloc_replaced = 1;
1805 /* Switch to runtime mode: any further failures in the dynamic
1806 * linker are a reportable failure rather than a fatal startup
1811 debug.bp = dl_debug_state;
1813 debug.base = ldso.base;
1817 if (replace_argv0) argv[0] = replace_argv0;
1821 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1825 static void prepare_lazy(struct dso *p)
1827 size_t dyn[DYN_CNT], n, flags1=0;
1828 decode_vec(p->dynv, dyn, DYN_CNT);
1829 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1830 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1832 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1833 if (NEED_MIPS_GOT_RELOCS) {
1834 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1835 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1838 p->lazy = calloc(n, 3*sizeof(size_t));
1840 error("Error preparing lazy relocation for %s: %m", p->name);
1841 longjmp(*rtld_fail, 1);
1843 p->lazy_next = lazy_head;
1847 void *dlopen(const char *file, int mode)
1849 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1850 struct tls_module *orig_tls_tail;
1851 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1856 if (!file) return head;
1858 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1859 pthread_rwlock_wrlock(&lock);
1863 orig_tls_tail = tls_tail;
1864 orig_tls_cnt = tls_cnt;
1865 orig_tls_offset = tls_offset;
1866 orig_tls_align = tls_align;
1867 orig_lazy_head = lazy_head;
1868 orig_syms_tail = syms_tail;
1870 noload = mode & RTLD_NOLOAD;
1873 if (setjmp(*rtld_fail)) {
1874 /* Clean up anything new that was (partially) loaded */
1875 revert_syms(orig_syms_tail);
1876 for (p=orig_tail->next; p; p=next) {
1878 while (p->td_index) {
1879 void *tmp = p->td_index->next;
1884 if (p->rpath != p->rpath_orig)
1890 if (!orig_tls_tail) libc.tls_head = 0;
1891 tls_tail = orig_tls_tail;
1892 if (tls_tail) tls_tail->next = 0;
1893 tls_cnt = orig_tls_cnt;
1894 tls_offset = orig_tls_offset;
1895 tls_align = orig_tls_align;
1896 lazy_head = orig_lazy_head;
1901 } else p = load_library(file, head);
1905 "Library %s is not already loaded" :
1906 "Error loading shared library %s: %m",
1911 /* First load handling */
1914 if (!p->relocated && (mode & RTLD_LAZY)) {
1916 for (i=0; p->deps[i]; i++)
1917 if (!p->deps[i]->relocated)
1918 prepare_lazy(p->deps[i]);
1920 if (!p->relocated || (mode & RTLD_GLOBAL)) {
1921 /* Make new symbols global, at least temporarily, so we can do
1922 * relocations. If not RTLD_GLOBAL, this is reverted below. */
1924 for (i=0; p->deps[i]; i++)
1925 add_syms(p->deps[i]);
1927 if (!p->relocated) {
1931 /* If RTLD_GLOBAL was not specified, undo any new additions
1932 * to the global symbol table. This is a nop if the library was
1933 * previously loaded and already global. */
1934 if (!(mode & RTLD_GLOBAL))
1935 revert_syms(orig_syms_tail);
1937 /* Processing of deferred lazy relocations must not happen until
1938 * the new libraries are committed; otherwise we could end up with
1939 * relocations resolved to symbol definitions that get removed. */
1943 if (tls_cnt != orig_tls_cnt)
1950 pthread_rwlock_unlock(&lock);
1951 if (p) do_init_fini(orig_tail);
1952 pthread_setcancelstate(cs, 0);
1956 hidden int __dl_invalid_handle(void *h)
1959 for (p=head; p; p=p->next) if (h==p) return 0;
1960 error("Invalid library handle %p", (void *)h);
1964 static void *addr2dso(size_t a)
1968 if (DL_FDPIC) for (p=head; p; p=p->next) {
1970 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1973 for (p=head; p; p=p->next) {
1974 if (DL_FDPIC && p->loadmap) {
1975 for (i=0; i<p->loadmap->nsegs; i++) {
1976 if (a-p->loadmap->segs[i].p_vaddr
1977 < p->loadmap->segs[i].p_memsz)
1982 size_t phcnt = p->phnum;
1983 size_t entsz = p->phentsize;
1984 size_t base = (size_t)p->base;
1985 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
1986 if (ph->p_type != PT_LOAD) continue;
1987 if (a-base-ph->p_vaddr < ph->p_memsz)
1990 if (a-(size_t)p->map < p->map_len)
1997 static void *do_dlsym(struct dso *p, const char *s, void *ra)
2000 uint32_t h = 0, gh = 0, *ght;
2002 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
2003 if (p == RTLD_DEFAULT) {
2005 } else if (p == RTLD_NEXT) {
2006 p = addr2dso((size_t)ra);
2010 struct symdef def = find_sym(p, s, 0);
2011 if (!def.sym) goto failed;
2012 if ((def.sym->st_info&0xf) == STT_TLS)
2013 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
2014 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
2015 return def.dso->funcdescs + (def.sym - def.dso->syms);
2016 return laddr(def.dso, def.sym->st_value);
2018 if (__dl_invalid_handle(p))
2020 if ((ght = p->ghashtab)) {
2022 sym = gnu_lookup(gh, ght, p, s);
2025 sym = sysv_lookup(s, h, p);
2027 if (sym && (sym->st_info&0xf) == STT_TLS)
2028 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
2029 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2030 return p->funcdescs + (sym - p->syms);
2031 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2032 return laddr(p, sym->st_value);
2033 for (i=0; p->deps[i]; i++) {
2034 if ((ght = p->deps[i]->ghashtab)) {
2035 if (!gh) gh = gnu_hash(s);
2036 sym = gnu_lookup(gh, ght, p->deps[i], s);
2038 if (!h) h = sysv_hash(s);
2039 sym = sysv_lookup(s, h, p->deps[i]);
2041 if (sym && (sym->st_info&0xf) == STT_TLS)
2042 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
2043 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2044 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
2045 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2046 return laddr(p->deps[i], sym->st_value);
2049 error("Symbol not found: %s", s);
2053 int dladdr(const void *addr_arg, Dl_info *info)
2055 size_t addr = (size_t)addr_arg;
2061 size_t besterr = -1;
2063 pthread_rwlock_rdlock(&lock);
2065 pthread_rwlock_unlock(&lock);
2070 strings = p->strings;
2071 nsym = count_syms(p);
2074 size_t idx = (addr-(size_t)p->funcdescs)
2075 / sizeof(*p->funcdescs);
2076 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2077 best = (size_t)(p->funcdescs + idx);
2078 bestsym = sym + idx;
2083 if (!best) for (; nsym; nsym--, sym++) {
2085 && (1<<(sym->st_info&0xf) & OK_TYPES)
2086 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2087 size_t symaddr = (size_t)laddr(p, sym->st_value);
2088 if (symaddr > addr || symaddr <= best)
2092 besterr = addr - symaddr;
2093 if (addr == symaddr)
2098 if (bestsym && besterr > bestsym->st_size-1) {
2103 info->dli_fname = p->name;
2104 info->dli_fbase = p->map;
2107 info->dli_sname = 0;
2108 info->dli_saddr = 0;
2112 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2113 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2114 info->dli_sname = strings + bestsym->st_name;
2115 info->dli_saddr = (void *)best;
2120 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2123 pthread_rwlock_rdlock(&lock);
2124 res = do_dlsym(p, s, ra);
2125 pthread_rwlock_unlock(&lock);
2129 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2131 struct dso *current;
2132 struct dl_phdr_info info;
2134 for(current = head; current;) {
2135 info.dlpi_addr = (uintptr_t)current->base;
2136 info.dlpi_name = current->name;
2137 info.dlpi_phdr = current->phdr;
2138 info.dlpi_phnum = current->phnum;
2139 info.dlpi_adds = gencnt;
2141 info.dlpi_tls_modid = current->tls_id;
2142 info.dlpi_tls_data = current->tls.image;
2144 ret = (callback)(&info, sizeof (info), data);
2146 if (ret != 0) break;
2148 pthread_rwlock_rdlock(&lock);
2149 current = current->next;
2150 pthread_rwlock_unlock(&lock);
2155 static void error(const char *fmt, ...)
2160 vdprintf(2, fmt, ap);
2166 __dl_vseterr(fmt, ap);