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;
81 char *rpath_orig, *rpath;
82 struct tls_module tls;
84 size_t relro_start, relro_end;
86 unsigned char *new_tls;
87 volatile int new_dtv_idx, new_tls_idx;
88 struct td_index *td_index;
89 struct dso *fini_next;
94 struct fdpic_loadmap *loadmap;
109 static struct builtin_tls {
114 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
116 #define ADDEND_LIMIT 4096
117 static size_t *saved_addends, *apply_addends_to;
119 static struct dso ldso;
120 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
121 static char *env_path, *sys_path;
122 static unsigned long long gencnt;
125 static int ldso_fail;
127 static int shutting_down;
128 static jmp_buf *rtld_fail;
129 static pthread_rwlock_t lock;
130 static struct debug debug;
131 static struct tls_module *tls_tail;
132 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
133 static size_t static_tls_cnt;
134 static pthread_mutex_t init_fini_lock;
135 static pthread_cond_t ctor_cond;
136 static struct dso *builtin_deps[2];
137 static struct dso **main_ctor_queue;
138 static struct fdpic_loadmap *app_loadmap;
139 static struct fdpic_dummy_loadmap app_dummy_loadmap;
141 struct debug *_dl_debug_addr = &debug;
143 extern hidden int __malloc_replaced;
145 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
147 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
149 weak_alias(__init_array_start, __init_array_end);
150 weak_alias(__fini_array_start, __fini_array_end);
152 static int dl_strcmp(const char *l, const char *r)
154 for (; *l==*r && *l; l++, r++);
155 return *(unsigned char *)l - *(unsigned char *)r;
157 #define strcmp(l,r) dl_strcmp(l,r)
159 /* Compute load address for a virtual address in a given dso. */
161 static void *laddr(const struct dso *p, size_t v)
164 if (!p->loadmap) return p->base + v;
165 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
166 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
168 static void *laddr_pg(const struct dso *p, size_t v)
171 size_t pgsz = PAGE_SIZE;
172 if (!p->loadmap) return p->base + v;
174 size_t a = p->loadmap->segs[j].p_vaddr;
175 size_t b = a + p->loadmap->segs[j].p_memsz;
181 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
183 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
184 laddr(p, v), (p)->got })
186 #define laddr(p, v) (void *)((p)->base + (v))
187 #define laddr_pg(p, v) laddr(p, v)
188 #define fpaddr(p, v) ((void (*)())laddr(p, v))
191 static void decode_vec(size_t *v, size_t *a, size_t cnt)
194 for (i=0; i<cnt; i++) a[i] = 0;
195 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
201 static int search_vec(size_t *v, size_t *r, size_t key)
203 for (; v[0]!=key; v+=2)
209 static uint32_t sysv_hash(const char *s0)
211 const unsigned char *s = (void *)s0;
217 return h & 0xfffffff;
220 static uint32_t gnu_hash(const char *s0)
222 const unsigned char *s = (void *)s0;
223 uint_fast32_t h = 5381;
229 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
232 Sym *syms = dso->syms;
233 Elf_Symndx *hashtab = dso->hashtab;
234 char *strings = dso->strings;
235 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
236 if ((!dso->versym || dso->versym[i] >= 0)
237 && (!strcmp(s, strings+syms[i].st_name)))
243 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
245 uint32_t nbuckets = hashtab[0];
246 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
247 uint32_t i = buckets[h1 % nbuckets];
251 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
253 for (h1 |= 1; ; i++) {
254 uint32_t h2 = *hashval++;
255 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
256 && !strcmp(s, dso->strings + dso->syms[i].st_name))
264 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
266 const size_t *bloomwords = (const void *)(hashtab+4);
267 size_t f = bloomwords[fofs & (hashtab[2]-1)];
268 if (!(f & fmask)) return 0;
270 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
271 if (!(f & 1)) return 0;
273 return gnu_lookup(h1, hashtab, dso, s);
276 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
277 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
279 #ifndef ARCH_SYM_REJECT_UND
280 #define ARCH_SYM_REJECT_UND(s) 0
283 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
285 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
286 size_t ghm = 1ul << gh % (8*sizeof(size_t));
287 struct symdef def = {0};
288 for (; dso; dso=dso->syms_next) {
290 if ((ght = dso->ghashtab)) {
291 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
293 if (!h) h = sysv_hash(s);
294 sym = sysv_lookup(s, h, dso);
298 if (need_def || (sym->st_info&0xf) == STT_TLS
299 || ARCH_SYM_REJECT_UND(sym))
302 if ((sym->st_info&0xf) != STT_TLS)
304 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
305 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
313 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
315 unsigned char *base = dso->base;
316 Sym *syms = dso->syms;
317 char *strings = dso->strings;
328 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
331 /* Only ldso's REL table needs addend saving/reuse. */
332 if (rel == apply_addends_to)
337 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
338 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
339 type = R_TYPE(rel[1]);
340 if (type == REL_NONE) continue;
341 reloc_addr = laddr(dso, rel[0]);
345 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
347 } else if (reuse_addends) {
348 /* Save original addend in stage 2 where the dso
349 * chain consists of just ldso; otherwise read back
350 * saved addend since the inline one was clobbered. */
352 saved_addends[save_slot] = *reloc_addr;
353 addend = saved_addends[save_slot++];
355 addend = *reloc_addr;
358 sym_index = R_SYM(rel[1]);
360 sym = syms + sym_index;
361 name = strings + sym->st_name;
362 ctx = type==REL_COPY ? head->syms_next : head;
363 def = (sym->st_info&0xf) == STT_SECTION
364 ? (struct symdef){ .dso = dso, .sym = sym }
365 : find_sym(ctx, name, type==REL_PLT);
366 if (!def.sym && (sym->st_shndx != SHN_UNDEF
367 || sym->st_info>>4 != STB_WEAK)) {
368 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
369 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
370 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
371 dso->lazy[3*dso->lazy_cnt+2] = addend;
375 error("Error relocating %s: %s: symbol not found",
377 if (runtime) longjmp(*rtld_fail, 1);
386 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
387 tls_val = def.sym ? def.sym->st_value : 0;
389 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
390 && runtime && def.dso->tls_id > static_tls_cnt) {
391 error("Error relocating %s: %s: initial-exec TLS "
392 "resolves to dynamic definition in %s",
393 dso->name, name, def.dso->name);
394 longjmp(*rtld_fail, 1);
401 addend -= (size_t)reloc_addr;
405 *reloc_addr = sym_val + addend;
408 *reloc_addr = (size_t)base + addend;
411 if (sym) *reloc_addr = sym_val + addend;
412 else *reloc_addr = (size_t)base + addend;
415 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
418 *(uint32_t *)reloc_addr = sym_val + addend
419 - (size_t)reloc_addr;
422 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
423 + (def.sym - def.dso->syms)) : 0;
425 case REL_FUNCDESC_VAL:
426 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
427 else *reloc_addr = sym_val;
428 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
431 *reloc_addr = def.dso->tls_id;
434 *reloc_addr = tls_val + addend - DTP_OFFSET;
438 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
442 *reloc_addr = tls_val - def.dso->tls.offset + addend;
445 *reloc_addr = def.dso->tls.offset - tls_val + addend;
449 if (stride<3) addend = reloc_addr[1];
450 if (runtime && def.dso->tls_id > static_tls_cnt) {
451 struct td_index *new = malloc(sizeof *new);
454 "Error relocating %s: cannot allocate TLSDESC for %s",
455 dso->name, sym ? name : "(local)" );
456 longjmp(*rtld_fail, 1);
458 new->next = dso->td_index;
460 new->args[0] = def.dso->tls_id;
461 new->args[1] = tls_val + addend - DTP_OFFSET;
462 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
463 reloc_addr[1] = (size_t)new;
465 reloc_addr[0] = (size_t)__tlsdesc_static;
467 reloc_addr[1] = tls_val + def.dso->tls.offset
470 reloc_addr[1] = tls_val - def.dso->tls.offset
474 #ifdef TLSDESC_BACKWARDS
475 /* Some archs (32-bit ARM at least) invert the order of
476 * the descriptor members. Fix them up here. */
477 size_t tmp = reloc_addr[0];
478 reloc_addr[0] = reloc_addr[1];
483 error("Error relocating %s: unsupported relocation type %d",
485 if (runtime) longjmp(*rtld_fail, 1);
491 static void redo_lazy_relocs()
493 struct dso *p = lazy_head, *next;
497 size_t size = p->lazy_cnt*3*sizeof(size_t);
499 do_relocs(p, p->lazy, size, 3);
501 p->lazy_next = lazy_head;
511 /* A huge hack: to make up for the wastefulness of shared libraries
512 * needing at least a page of dirty memory even if they have no global
513 * data, we reclaim the gaps at the beginning and end of writable maps
514 * and "donate" them to the heap. */
516 static void reclaim(struct dso *dso, size_t start, size_t end)
518 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
519 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
520 if (start >= end) return;
521 char *base = laddr_pg(dso, start);
522 __malloc_donate(base, base+(end-start));
525 static void reclaim_gaps(struct dso *dso)
527 Phdr *ph = dso->phdr;
528 size_t phcnt = dso->phnum;
530 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
531 if (ph->p_type!=PT_LOAD) continue;
532 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
533 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
534 reclaim(dso, ph->p_vaddr+ph->p_memsz,
535 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
539 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
541 static int no_map_fixed;
544 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
545 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
549 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
550 if (flags & MAP_ANONYMOUS) {
555 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
556 for (q=p; n; q+=r, off+=r, n-=r) {
558 if (r < 0 && errno != EINTR) return MAP_FAILED;
567 static void unmap_library(struct dso *dso)
571 for (i=0; i<dso->loadmap->nsegs; i++) {
572 if (!dso->loadmap->segs[i].p_memsz)
574 munmap((void *)dso->loadmap->segs[i].addr,
575 dso->loadmap->segs[i].p_memsz);
578 } else if (dso->map && dso->map_len) {
579 munmap(dso->map, dso->map_len);
583 static void *map_library(int fd, struct dso *dso)
585 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
586 void *allocated_buf=0;
588 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
589 size_t this_min, this_max;
595 unsigned char *map=MAP_FAILED, *base;
600 ssize_t l = read(fd, buf, sizeof buf);
603 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
605 phsize = eh->e_phentsize * eh->e_phnum;
606 if (phsize > sizeof buf - sizeof *eh) {
607 allocated_buf = malloc(phsize);
608 if (!allocated_buf) return 0;
609 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
610 if (l < 0) goto error;
611 if (l != phsize) goto noexec;
612 ph = ph0 = allocated_buf;
613 } else if (eh->e_phoff + phsize > l) {
614 l = pread(fd, buf+1, phsize, eh->e_phoff);
615 if (l < 0) goto error;
616 if (l != phsize) goto noexec;
617 ph = ph0 = (void *)(buf + 1);
619 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
621 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
622 if (ph->p_type == PT_DYNAMIC) {
624 } else if (ph->p_type == PT_TLS) {
625 tls_image = ph->p_vaddr;
626 dso->tls.align = ph->p_align;
627 dso->tls.len = ph->p_filesz;
628 dso->tls.size = ph->p_memsz;
629 } else if (ph->p_type == PT_GNU_RELRO) {
630 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
631 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
632 } else if (ph->p_type == PT_GNU_STACK) {
633 if (!runtime && ph->p_memsz > __default_stacksize) {
634 __default_stacksize =
635 ph->p_memsz < DEFAULT_STACK_MAX ?
636 ph->p_memsz : DEFAULT_STACK_MAX;
639 if (ph->p_type != PT_LOAD) continue;
641 if (ph->p_vaddr < addr_min) {
642 addr_min = ph->p_vaddr;
643 off_start = ph->p_offset;
644 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
645 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
646 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
648 if (ph->p_vaddr+ph->p_memsz > addr_max) {
649 addr_max = ph->p_vaddr+ph->p_memsz;
652 if (!dyn) goto noexec;
653 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
654 dso->loadmap = calloc(1, sizeof *dso->loadmap
655 + nsegs * sizeof *dso->loadmap->segs);
656 if (!dso->loadmap) goto error;
657 dso->loadmap->nsegs = nsegs;
658 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
659 if (ph->p_type != PT_LOAD) continue;
660 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
661 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
662 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
663 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
665 fd, ph->p_offset & -PAGE_SIZE);
666 if (map == MAP_FAILED) {
670 dso->loadmap->segs[i].addr = (size_t)map +
671 (ph->p_vaddr & PAGE_SIZE-1);
672 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
673 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
675 if (prot & PROT_WRITE) {
676 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
678 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
679 size_t pgend = brk + ph->p_memsz - ph->p_filesz
680 + PAGE_SIZE-1 & -PAGE_SIZE;
681 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
683 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
684 -1, off_start) == MAP_FAILED)
686 memset(map + brk, 0, pgbrk-brk);
689 map = (void *)dso->loadmap->segs[0].addr;
693 addr_max += PAGE_SIZE-1;
694 addr_max &= -PAGE_SIZE;
695 addr_min &= -PAGE_SIZE;
696 off_start &= -PAGE_SIZE;
697 map_len = addr_max - addr_min + off_start;
698 /* The first time, we map too much, possibly even more than
699 * the length of the file. This is okay because we will not
700 * use the invalid part; we just need to reserve the right
701 * amount of virtual address space to map over later. */
702 map = DL_NOMMU_SUPPORT
703 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
704 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
705 : mmap((void *)addr_min, map_len, prot,
706 MAP_PRIVATE, fd, off_start);
707 if (map==MAP_FAILED) goto error;
709 dso->map_len = map_len;
710 /* If the loaded file is not relocatable and the requested address is
711 * not available, then the load operation must fail. */
712 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
716 base = map - addr_min;
719 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
720 if (ph->p_type != PT_LOAD) continue;
721 /* Check if the programs headers are in this load segment, and
722 * if so, record the address for use by dl_iterate_phdr. */
723 if (!dso->phdr && eh->e_phoff >= ph->p_offset
724 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
725 dso->phdr = (void *)(base + ph->p_vaddr
726 + (eh->e_phoff-ph->p_offset));
727 dso->phnum = eh->e_phnum;
728 dso->phentsize = eh->e_phentsize;
730 this_min = ph->p_vaddr & -PAGE_SIZE;
731 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
732 off_start = ph->p_offset & -PAGE_SIZE;
733 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
734 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
735 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
736 /* Reuse the existing mapping for the lowest-address LOAD */
737 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
738 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
740 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
741 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
742 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
743 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
744 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)
748 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
749 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
750 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
757 dso->dynv = laddr(dso, dyn);
758 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
764 if (map!=MAP_FAILED) unmap_library(dso);
769 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
774 s += strspn(s, ":\n");
775 l = strcspn(s, ":\n");
776 if (l-1 >= INT_MAX) return -1;
777 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
778 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
786 /* Any negative value but -1 will inhibit
787 * futher path search. */
795 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
798 const char *s, *t, *origin;
800 if (p->rpath || !p->rpath_orig) return 0;
801 if (!strchr(p->rpath_orig, '$')) {
802 p->rpath = p->rpath_orig;
807 while ((t=strchr(s, '$'))) {
808 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
813 if (n > SSIZE_MAX/PATH_MAX) return 0;
815 if (p->kernel_mapped) {
816 /* $ORIGIN searches cannot be performed for the main program
817 * when it is suid/sgid/AT_SECURE. This is because the
818 * pathname is under the control of the caller of execve.
819 * For libraries, however, $ORIGIN can be processed safely
820 * since the library's pathname came from a trusted source
821 * (either system paths or a call to dlopen). */
824 l = readlink("/proc/self/exe", buf, buf_size);
825 if (l == -1) switch (errno) {
840 t = strrchr(origin, '/');
844 /* Normally p->name will always be an absolute or relative
845 * pathname containing at least one '/' character, but in the
846 * case where ldso was invoked as a command to execute a
847 * program in the working directory, app.name may not. Fix. */
851 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
852 if (libc.secure && *origin != '/')
854 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
855 if (!p->rpath) return -1;
859 while ((t=strchr(s, '$'))) {
862 memcpy(d, origin, l);
864 /* It was determined previously that the '$' is followed
865 * either by "ORIGIN" or "{ORIGIN}". */
866 s = t + 7 + 2*(t[1]=='{');
872 static void decode_dyn(struct dso *p)
875 decode_vec(p->dynv, dyn, DYN_CNT);
876 p->syms = laddr(p, dyn[DT_SYMTAB]);
877 p->strings = laddr(p, dyn[DT_STRTAB]);
878 if (dyn[0]&(1<<DT_HASH))
879 p->hashtab = laddr(p, dyn[DT_HASH]);
880 if (dyn[0]&(1<<DT_RPATH))
881 p->rpath_orig = p->strings + dyn[DT_RPATH];
882 if (dyn[0]&(1<<DT_RUNPATH))
883 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
884 if (dyn[0]&(1<<DT_PLTGOT))
885 p->got = laddr(p, dyn[DT_PLTGOT]);
886 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
887 p->ghashtab = laddr(p, *dyn);
888 if (search_vec(p->dynv, dyn, DT_VERSYM))
889 p->versym = laddr(p, *dyn);
892 static size_t count_syms(struct dso *p)
894 if (p->hashtab) return p->hashtab[1];
897 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
899 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
900 if (buckets[i] > nsym)
904 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
906 while (!(*hashval++ & 1));
911 static void *dl_mmap(size_t n)
914 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
916 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
918 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
920 return p == MAP_FAILED ? 0 : p;
923 static void makefuncdescs(struct dso *p)
925 static int self_done;
926 size_t nsym = count_syms(p);
927 size_t i, size = nsym * sizeof(*p->funcdescs);
930 p->funcdescs = dl_mmap(size);
933 p->funcdescs = malloc(size);
936 if (!runtime) a_crash();
937 error("Error allocating function descriptors for %s", p->name);
938 longjmp(*rtld_fail, 1);
940 for (i=0; i<nsym; i++) {
941 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
942 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
943 p->funcdescs[i].got = p->got;
945 p->funcdescs[i].addr = 0;
946 p->funcdescs[i].got = 0;
951 static struct dso *load_library(const char *name, struct dso *needed_by)
953 char buf[2*NAME_MAX+2];
954 const char *pathname;
956 struct dso *p, temp_dso = {0};
968 /* Catch and block attempts to reload the implementation itself */
969 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
970 static const char reserved[] =
971 "c.pthread.rt.m.dl.util.xnet.";
972 const char *rp, *next;
973 for (rp=reserved; *rp; rp=next) {
974 next = strchr(rp, '.') + 1;
975 if (strncmp(name+3, rp, next-rp) == 0)
980 /* Track which names have been resolved
981 * and only report each one once. */
982 static unsigned reported;
983 unsigned mask = 1U<<(rp-reserved);
984 if (!(reported & mask)) {
986 dprintf(1, "\t%s => %s (%p)\n",
994 if (!strcmp(name, ldso.name)) is_self = 1;
1003 if (strchr(name, '/')) {
1005 fd = open(name, O_RDONLY|O_CLOEXEC);
1007 /* Search for the name to see if it's already loaded */
1008 for (p=head->next; p; p=p->next) {
1009 if (p->shortname && !strcmp(p->shortname, name)) {
1013 if (strlen(name) > NAME_MAX) return 0;
1015 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1016 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1017 if (fixup_rpath(p, buf, sizeof buf) < 0)
1018 fd = -2; /* Inhibit further search. */
1020 fd = path_open(name, p->rpath, buf, sizeof buf);
1026 if (ldso.name[0]=='/') {
1028 for (s=t=z=ldso.name; *s; s++)
1029 if (*s=='/') z=t, t=s;
1030 prefix_len = z-ldso.name;
1031 if (prefix_len < PATH_MAX)
1038 char etc_ldso_path[prefix_len + 1
1039 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1040 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1041 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1042 (int)prefix_len, prefix);
1043 FILE *f = fopen(etc_ldso_path, "rbe");
1045 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1050 } else if (errno != ENOENT) {
1054 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1055 fd = path_open(name, sys_path, buf, sizeof buf);
1059 if (fd < 0) return 0;
1060 if (fstat(fd, &st) < 0) {
1064 for (p=head->next; p; p=p->next) {
1065 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1066 /* If this library was previously loaded with a
1067 * pathname but a search found the same inode,
1068 * setup its shortname so it can be found by name. */
1069 if (!p->shortname && pathname != name)
1070 p->shortname = strrchr(p->name, '/')+1;
1075 map = noload ? 0 : map_library(fd, &temp_dso);
1079 /* Avoid the danger of getting two versions of libc mapped into the
1080 * same process when an absolute pathname was used. The symbols
1081 * checked are chosen to catch both musl and glibc, and to avoid
1082 * false positives from interposition-hack libraries. */
1083 decode_dyn(&temp_dso);
1084 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1085 find_sym(&temp_dso, "stdin", 1).sym) {
1086 unmap_library(&temp_dso);
1087 return load_library("libc.so", needed_by);
1089 /* Past this point, if we haven't reached runtime yet, ldso has
1090 * committed either to use the mapped library or to abort execution.
1091 * Unmapping is not possible, so we can safely reclaim gaps. */
1092 if (!runtime) reclaim_gaps(&temp_dso);
1094 /* Allocate storage for the new DSO. When there is TLS, this
1095 * storage must include a reservation for all pre-existing
1096 * threads to obtain copies of both the new TLS, and an
1097 * extended DTV capable of storing an additional slot for
1098 * the newly-loaded DSO. */
1099 alloc_size = sizeof *p + strlen(pathname) + 1;
1100 if (runtime && temp_dso.tls.image) {
1101 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1102 + sizeof(void *) * (tls_cnt+3);
1103 n_th = libc.threads_minus_1 + 1;
1104 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1105 else alloc_size += n_th * per_th;
1107 p = calloc(1, alloc_size);
1109 unmap_library(&temp_dso);
1112 memcpy(p, &temp_dso, sizeof temp_dso);
1115 p->needed_by = needed_by;
1117 p->runtime_loaded = runtime;
1118 strcpy(p->name, pathname);
1119 /* Add a shortname only if name arg was not an explicit pathname. */
1120 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1122 p->tls_id = ++tls_cnt;
1123 tls_align = MAXP2(tls_align, p->tls.align);
1125 p->tls.offset = tls_offset + ( (tls_align-1) &
1126 -(tls_offset + (uintptr_t)p->tls.image) );
1127 tls_offset += p->tls.size;
1129 tls_offset += p->tls.size + p->tls.align - 1;
1130 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1132 p->tls.offset = tls_offset;
1134 p->new_dtv = (void *)(-sizeof(size_t) &
1135 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1136 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1137 if (tls_tail) tls_tail->next = &p->tls;
1138 else libc.tls_head = &p->tls;
1146 if (DL_FDPIC) makefuncdescs(p);
1148 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1153 static void load_direct_deps(struct dso *p)
1157 if (p->deps) return;
1158 /* For head, all preloads are direct pseudo-dependencies.
1159 * Count and include them now to avoid realloc later. */
1160 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1162 for (i=0; p->dynv[i]; i+=2)
1163 if (p->dynv[i] == DT_NEEDED) cnt++;
1164 /* Use builtin buffer for apps with no external deps, to
1165 * preserve property of no runtime failure paths. */
1166 p->deps = (p==head && cnt<2) ? builtin_deps :
1167 calloc(cnt+1, sizeof *p->deps);
1169 error("Error loading dependencies for %s", p->name);
1170 if (runtime) longjmp(*rtld_fail, 1);
1173 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1175 for (i=0; p->dynv[i]; i+=2) {
1176 if (p->dynv[i] != DT_NEEDED) continue;
1177 struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
1179 error("Error loading shared library %s: %m (needed by %s)",
1180 p->strings + p->dynv[i+1], p->name);
1181 if (runtime) longjmp(*rtld_fail, 1);
1184 p->deps[cnt++] = dep;
1187 p->ndeps_direct = cnt;
1190 static void load_deps(struct dso *p)
1192 if (p->deps) return;
1193 for (; p; p=p->next)
1194 load_direct_deps(p);
1197 static void extend_bfs_deps(struct dso *p)
1199 size_t i, j, cnt, ndeps_all;
1202 /* Can't use realloc if the original p->deps was allocated at
1203 * program entry and malloc has been replaced, or if it's
1204 * the builtin non-allocated trivial main program deps array. */
1205 int no_realloc = (__malloc_replaced && !p->runtime_loaded)
1206 || p->deps == builtin_deps;
1208 if (p->bfs_built) return;
1209 ndeps_all = p->ndeps_direct;
1211 /* Mark existing (direct) deps so they won't be duplicated. */
1212 for (i=0; p->deps[i]; i++)
1213 p->deps[i]->mark = 1;
1215 /* For each dependency already in the list, copy its list of direct
1216 * dependencies to the list, excluding any items already in the
1217 * list. Note that the list this loop iterates over will grow during
1218 * the loop, but since duplicates are excluded, growth is bounded. */
1219 for (i=0; p->deps[i]; i++) {
1220 struct dso *dep = p->deps[i];
1221 for (j=cnt=0; j<dep->ndeps_direct; j++)
1222 if (!dep->deps[j]->mark) cnt++;
1224 malloc(sizeof(*tmp) * (ndeps_all+cnt+1)) :
1225 realloc(p->deps, sizeof(*tmp) * (ndeps_all+cnt+1));
1227 error("Error recording dependencies for %s", p->name);
1228 if (runtime) longjmp(*rtld_fail, 1);
1232 memcpy(tmp, p->deps, sizeof(*tmp) * (ndeps_all+1));
1236 for (j=0; j<dep->ndeps_direct; j++) {
1237 if (dep->deps[j]->mark) continue;
1238 dep->deps[j]->mark = 1;
1239 p->deps[ndeps_all++] = dep->deps[j];
1241 p->deps[ndeps_all] = 0;
1244 for (p=head; p; p=p->next)
1248 static void load_preload(char *s)
1252 for (z=s; *z; s=z) {
1253 for ( ; *s && (isspace(*s) || *s==':'); s++);
1254 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1262 static void add_syms(struct dso *p)
1264 if (!p->syms_next && syms_tail != p) {
1265 syms_tail->syms_next = p;
1270 static void revert_syms(struct dso *old_tail)
1272 struct dso *p, *next;
1273 /* Chop off the tail of the list of dsos that participate in
1274 * the global symbol table, reverting them to RTLD_LOCAL. */
1275 for (p=old_tail; p; p=next) {
1276 next = p->syms_next;
1279 syms_tail = old_tail;
1282 static void do_mips_relocs(struct dso *p, size_t *got)
1284 size_t i, j, rel[2];
1285 unsigned char *base = p->base;
1286 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1290 while (i--) *got++ += (size_t)base;
1292 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1293 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1294 Sym *sym = p->syms + j;
1295 rel[0] = (unsigned char *)got - base;
1296 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1297 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1298 do_relocs(p, rel, sizeof rel, 2);
1302 static void reloc_all(struct dso *p)
1304 size_t dyn[DYN_CNT];
1305 for (; p; p=p->next) {
1306 if (p->relocated) continue;
1307 decode_vec(p->dynv, dyn, DYN_CNT);
1308 if (NEED_MIPS_GOT_RELOCS)
1309 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1310 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1311 2+(dyn[DT_PLTREL]==DT_RELA));
1312 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1313 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1315 if (head != &ldso && p->relro_start != p->relro_end &&
1316 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1317 && errno != ENOSYS) {
1318 error("Error relocating %s: RELRO protection failed: %m",
1320 if (runtime) longjmp(*rtld_fail, 1);
1327 static void kernel_mapped_dso(struct dso *p)
1329 size_t min_addr = -1, max_addr = 0, cnt;
1331 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1332 if (ph->p_type == PT_DYNAMIC) {
1333 p->dynv = laddr(p, ph->p_vaddr);
1334 } else if (ph->p_type == PT_GNU_RELRO) {
1335 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1336 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1337 } else if (ph->p_type == PT_GNU_STACK) {
1338 if (!runtime && ph->p_memsz > __default_stacksize) {
1339 __default_stacksize =
1340 ph->p_memsz < DEFAULT_STACK_MAX ?
1341 ph->p_memsz : DEFAULT_STACK_MAX;
1344 if (ph->p_type != PT_LOAD) continue;
1345 if (ph->p_vaddr < min_addr)
1346 min_addr = ph->p_vaddr;
1347 if (ph->p_vaddr+ph->p_memsz > max_addr)
1348 max_addr = ph->p_vaddr+ph->p_memsz;
1350 min_addr &= -PAGE_SIZE;
1351 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1352 p->map = p->base + min_addr;
1353 p->map_len = max_addr - min_addr;
1354 p->kernel_mapped = 1;
1357 void __libc_exit_fini()
1360 size_t dyn[DYN_CNT];
1361 int self = __pthread_self()->tid;
1363 /* Take both locks before setting shutting_down, so that
1364 * either lock is sufficient to read its value. The lock
1365 * order matches that in dlopen to avoid deadlock. */
1366 pthread_rwlock_wrlock(&lock);
1367 pthread_mutex_lock(&init_fini_lock);
1369 pthread_rwlock_unlock(&lock);
1370 for (p=fini_head; p; p=p->fini_next) {
1371 while (p->ctor_visitor && p->ctor_visitor!=self)
1372 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1373 if (!p->constructed) continue;
1374 decode_vec(p->dynv, dyn, DYN_CNT);
1375 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1376 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1377 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1378 while (n--) ((void (*)(void))*--fn)();
1380 #ifndef NO_LEGACY_INITFINI
1381 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1382 fpaddr(p, dyn[DT_FINI])();
1387 static struct dso **queue_ctors(struct dso *dso)
1389 size_t cnt, qpos, spos, i;
1390 struct dso *p, **queue, **stack;
1392 if (ldd_mode) return 0;
1394 /* Bound on queue size is the total number of indirect deps.
1395 * If a bfs deps list was built, we can use it. Otherwise,
1396 * bound by the total number of DSOs, which is always safe and
1397 * is reasonable we use it (for main app at startup). */
1398 if (dso->bfs_built) {
1399 for (cnt=0; dso->deps[cnt]; cnt++)
1400 dso->deps[cnt]->mark = 0;
1401 cnt++; /* self, not included in deps */
1403 for (cnt=0, p=head; p; cnt++, p=p->next)
1406 cnt++; /* termination slot */
1407 stack = queue = calloc(cnt, sizeof *queue);
1410 error("Error allocating constructor queue: %m\n");
1411 if (runtime) longjmp(*rtld_fail, 1);
1415 /* Opposite ends of the allocated buffer serve as an output queue
1416 * and a working stack. Setup initial stack with just the argument
1417 * dso and initial queue empty... */
1420 stack[--spos] = dso;
1424 /* Then perform pseudo-DFS sort, but ignoring circular deps. */
1427 while (p->next_dep < p->ndeps_direct) {
1428 if (p->deps[p->next_dep]->mark) {
1432 p = p->deps[p->next_dep];
1440 for (i=0; i<qpos; i++) queue[i]->mark = 0;
1445 static void do_init_fini(struct dso **queue)
1448 size_t dyn[DYN_CNT], i;
1449 int self = __pthread_self()->tid;
1451 pthread_mutex_lock(&init_fini_lock);
1452 for (i=0; (p=queue[i]); i++) {
1453 while ((p->ctor_visitor && p->ctor_visitor!=self) || shutting_down)
1454 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1455 if (p->ctor_visitor || p->constructed)
1457 if (p->constructed) continue;
1458 p->ctor_visitor = self;
1460 decode_vec(p->dynv, dyn, DYN_CNT);
1461 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1462 p->fini_next = fini_head;
1466 pthread_mutex_unlock(&init_fini_lock);
1468 #ifndef NO_LEGACY_INITFINI
1469 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1470 fpaddr(p, dyn[DT_INIT])();
1472 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1473 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1474 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1475 while (n--) ((void (*)(void))*fn++)();
1478 pthread_mutex_lock(&init_fini_lock);
1479 p->ctor_visitor = 0;
1481 pthread_cond_broadcast(&ctor_cond);
1483 pthread_mutex_unlock(&init_fini_lock);
1486 void __libc_start_init(void)
1488 do_init_fini(main_ctor_queue);
1489 if (!__malloc_replaced) free(main_ctor_queue);
1490 main_ctor_queue = 0;
1493 static void dl_debug_state(void)
1497 weak_alias(dl_debug_state, _dl_debug_state);
1499 void __init_tls(size_t *auxv)
1503 static void update_tls_size()
1505 libc.tls_cnt = tls_cnt;
1506 libc.tls_align = tls_align;
1507 libc.tls_size = ALIGN(
1508 (1+tls_cnt) * sizeof(void *) +
1510 sizeof(struct pthread) +
1515 static void install_new_tls(void)
1518 pthread_t self = __pthread_self(), td;
1519 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1520 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1523 size_t old_cnt = self->dtv[0];
1525 __block_app_sigs(&set);
1527 /* Copy existing dtv contents from all existing threads. */
1528 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1529 memcpy(newdtv+i, td->dtv,
1530 (old_cnt+1)*sizeof(uintptr_t));
1531 newdtv[i][0] = tls_cnt;
1533 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1534 for (p=head; ; p=p->next) {
1535 if (p->tls_id <= old_cnt) continue;
1536 unsigned char *mem = p->new_tls;
1537 for (j=0; j<i; j++) {
1538 unsigned char *new = mem;
1539 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1541 memcpy(new, p->tls.image, p->tls.len);
1542 newdtv[j][p->tls_id] =
1543 (uintptr_t)new + DTP_OFFSET;
1544 mem += p->tls.size + p->tls.align;
1546 if (p->tls_id == tls_cnt) break;
1549 /* Broadcast barrier to ensure contents of new dtv is visible
1550 * if the new dtv pointer is. The __membarrier function has a
1551 * fallback emulation using signals for kernels that lack the
1552 * feature at the syscall level. */
1554 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1556 /* Install new dtv for each thread. */
1557 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1558 td->dtv = td->dtv_copy = newdtv[j];
1562 __restore_sigs(&set);
1565 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1566 * following stage 2 and stage 3 functions via primitive symbolic lookup
1567 * since it does not have access to their addresses to begin with. */
1569 /* Stage 2 of the dynamic linker is called after relative relocations
1570 * have been processed. It can make function calls to static functions
1571 * and access string literals and static data, but cannot use extern
1572 * symbols. Its job is to perform symbolic relocations on the dynamic
1573 * linker itself, but some of the relocations performed may need to be
1574 * replaced later due to copy relocations in the main program. */
1576 hidden void __dls2(unsigned char *base, size_t *sp)
1579 void *p1 = (void *)sp[-2];
1580 void *p2 = (void *)sp[-1];
1582 size_t *auxv, aux[AUX_CNT];
1583 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1585 decode_vec(auxv, aux, AUX_CNT);
1586 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1587 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1589 app_loadmap = p2 ? p1 : 0;
1590 ldso.loadmap = p2 ? p2 : p1;
1591 ldso.base = laddr(&ldso, 0);
1595 Ehdr *ehdr = (void *)ldso.base;
1596 ldso.name = ldso.shortname = "libc.so";
1597 ldso.phnum = ehdr->e_phnum;
1598 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1599 ldso.phentsize = ehdr->e_phentsize;
1600 kernel_mapped_dso(&ldso);
1603 if (DL_FDPIC) makefuncdescs(&ldso);
1605 /* Prepare storage for to save clobbered REL addends so they
1606 * can be reused in stage 3. There should be very few. If
1607 * something goes wrong and there are a huge number, abort
1608 * instead of risking stack overflow. */
1609 size_t dyn[DYN_CNT];
1610 decode_vec(ldso.dynv, dyn, DYN_CNT);
1611 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1612 size_t rel_size = dyn[DT_RELSZ];
1613 size_t symbolic_rel_cnt = 0;
1614 apply_addends_to = rel;
1615 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1616 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1617 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1618 size_t addends[symbolic_rel_cnt+1];
1619 saved_addends = addends;
1626 /* Call dynamic linker stage-2b, __dls2b, looking it up
1627 * symbolically as a barrier against moving the address
1628 * load across the above relocation processing. */
1629 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1630 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
1631 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
1634 /* Stage 2b sets up a valid thread pointer, which requires relocations
1635 * completed in stage 2, and on which stage 3 is permitted to depend.
1636 * This is done as a separate stage, with symbolic lookup as a barrier,
1637 * so that loads of the thread pointer and &errno can be pure/const and
1638 * thereby hoistable. */
1640 _Noreturn void __dls2b(size_t *sp)
1642 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1643 * use during dynamic linking. If possible it will also serve as the
1644 * thread pointer at runtime. */
1645 libc.tls_size = sizeof builtin_tls;
1646 libc.tls_align = tls_align;
1647 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1651 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1652 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1653 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1656 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1657 * fully functional. Its job is to load (if not already loaded) and
1658 * process dependencies and relocations for the main application and
1659 * transfer control to its entry point. */
1661 _Noreturn void __dls3(size_t *sp)
1663 static struct dso app, vdso;
1664 size_t aux[AUX_CNT], *auxv;
1666 char *env_preload=0;
1667 char *replace_argv0=0;
1670 char **argv = (void *)(sp+1);
1671 char **argv_orig = argv;
1672 char **envp = argv+argc+1;
1674 /* Find aux vector just past environ[] and use it to initialize
1675 * global data that may be needed before we can make syscalls. */
1677 for (i=argc+1; argv[i]; i++);
1678 libc.auxv = auxv = (void *)(argv+i+1);
1679 decode_vec(auxv, aux, AUX_CNT);
1680 __hwcap = aux[AT_HWCAP];
1681 libc.page_size = aux[AT_PAGESZ];
1682 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1683 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1685 /* Only trust user/env if kernel says we're not suid/sgid */
1687 env_path = getenv("LD_LIBRARY_PATH");
1688 env_preload = getenv("LD_PRELOAD");
1691 /* If the main program was already loaded by the kernel,
1692 * AT_PHDR will point to some location other than the dynamic
1693 * linker's program headers. */
1694 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1695 size_t interp_off = 0;
1696 size_t tls_image = 0;
1697 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1698 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1699 app.phnum = aux[AT_PHNUM];
1700 app.phentsize = aux[AT_PHENT];
1701 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1702 if (phdr->p_type == PT_PHDR)
1703 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1704 else if (phdr->p_type == PT_INTERP)
1705 interp_off = (size_t)phdr->p_vaddr;
1706 else if (phdr->p_type == PT_TLS) {
1707 tls_image = phdr->p_vaddr;
1708 app.tls.len = phdr->p_filesz;
1709 app.tls.size = phdr->p_memsz;
1710 app.tls.align = phdr->p_align;
1713 if (DL_FDPIC) app.loadmap = app_loadmap;
1714 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1715 if (interp_off) ldso.name = laddr(&app, interp_off);
1716 if ((aux[0] & (1UL<<AT_EXECFN))
1717 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1718 app.name = (char *)aux[AT_EXECFN];
1721 kernel_mapped_dso(&app);
1724 char *ldname = argv[0];
1725 size_t l = strlen(ldname);
1726 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1728 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1729 char *opt = argv[0]+2;
1730 *argv++ = (void *)-1;
1733 } else if (!memcmp(opt, "list", 5)) {
1735 } else if (!memcmp(opt, "library-path", 12)) {
1736 if (opt[12]=='=') env_path = opt+13;
1737 else if (opt[12]) *argv = 0;
1738 else if (*argv) env_path = *argv++;
1739 } else if (!memcmp(opt, "preload", 7)) {
1740 if (opt[7]=='=') env_preload = opt+8;
1741 else if (opt[7]) *argv = 0;
1742 else if (*argv) env_preload = *argv++;
1743 } else if (!memcmp(opt, "argv0", 5)) {
1744 if (opt[5]=='=') replace_argv0 = opt+6;
1745 else if (opt[5]) *argv = 0;
1746 else if (*argv) replace_argv0 = *argv++;
1751 argv[-1] = (void *)(argc - (argv-argv_orig));
1753 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1755 "Dynamic Program Loader\n"
1756 "Usage: %s [options] [--] pathname%s\n",
1757 __libc_version, ldname,
1758 ldd_mode ? "" : " [args]");
1761 fd = open(argv[0], O_RDONLY);
1763 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1766 Ehdr *ehdr = (void *)map_library(fd, &app);
1768 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1774 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1775 /* Find the name that would have been used for the dynamic
1776 * linker had ldd not taken its place. */
1778 for (i=0; i<app.phnum; i++) {
1779 if (app.phdr[i].p_type == PT_INTERP)
1780 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1782 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1786 libc.tls_head = tls_tail = &app.tls;
1787 app.tls_id = tls_cnt = 1;
1789 app.tls.offset = GAP_ABOVE_TP;
1790 app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
1791 tls_offset = app.tls.offset + app.tls.size
1792 + ( -((uintptr_t)app.tls.image + app.tls.size)
1793 & (app.tls.align-1) );
1795 tls_offset = app.tls.offset = app.tls.size
1796 + ( -((uintptr_t)app.tls.image + app.tls.size)
1797 & (app.tls.align-1) );
1799 tls_align = MAXP2(tls_align, app.tls.align);
1803 makefuncdescs(&app);
1805 app.loadmap = (void *)&app_dummy_loadmap;
1806 app.loadmap->nsegs = 1;
1807 app.loadmap->segs[0].addr = (size_t)app.map;
1808 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1810 app.loadmap->segs[0].p_memsz = app.map_len;
1812 argv[-3] = (void *)app.loadmap;
1815 /* Initial dso chain consists only of the app. */
1816 head = tail = syms_tail = &app;
1818 /* Donate unused parts of app and library mapping to malloc */
1820 reclaim_gaps(&ldso);
1822 /* Load preload/needed libraries, add symbols to global namespace. */
1823 if (env_preload) load_preload(env_preload);
1825 for (struct dso *p=head; p; p=p->next)
1828 /* Attach to vdso, if provided by the kernel, last so that it does
1829 * not become part of the global namespace. */
1830 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1831 Ehdr *ehdr = (void *)vdso_base;
1832 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1833 vdso.phnum = ehdr->e_phnum;
1834 vdso.phentsize = ehdr->e_phentsize;
1835 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1836 if (phdr->p_type == PT_DYNAMIC)
1837 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1838 if (phdr->p_type == PT_LOAD)
1839 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1842 vdso.shortname = "linux-gate.so.1";
1850 for (i=0; app.dynv[i]; i+=2) {
1851 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1852 app.dynv[i+1] = (size_t)&debug;
1853 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1854 size_t *ptr = (size_t *) app.dynv[i+1];
1855 *ptr = (size_t)&debug;
1859 /* This must be done before final relocations, since it calls
1860 * malloc, which may be provided by the application. Calling any
1861 * application code prior to the jump to its entry point is not
1862 * valid in our model and does not work with FDPIC, where there
1863 * are additional relocation-like fixups that only the entry point
1864 * code can see to perform. */
1865 main_ctor_queue = queue_ctors(&app);
1867 /* The main program must be relocated LAST since it may contin
1868 * copy relocations which depend on libraries' relocations. */
1869 reloc_all(app.next);
1873 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1874 void *initial_tls = calloc(libc.tls_size, 1);
1876 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1877 argv[0], libc.tls_size);
1880 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1884 size_t tmp_tls_size = libc.tls_size;
1885 pthread_t self = __pthread_self();
1886 /* Temporarily set the tls size to the full size of
1887 * builtin_tls so that __copy_tls will use the same layout
1888 * as it did for before. Then check, just to be safe. */
1889 libc.tls_size = sizeof builtin_tls;
1890 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1891 libc.tls_size = tmp_tls_size;
1893 static_tls_cnt = tls_cnt;
1895 if (ldso_fail) _exit(127);
1896 if (ldd_mode) _exit(0);
1898 /* Determine if malloc was interposed by a replacement implementation
1899 * so that calloc and the memalign family can harden against the
1900 * possibility of incomplete replacement. */
1901 if (find_sym(head, "malloc", 1).dso != &ldso)
1902 __malloc_replaced = 1;
1904 /* Switch to runtime mode: any further failures in the dynamic
1905 * linker are a reportable failure rather than a fatal startup
1910 debug.bp = dl_debug_state;
1912 debug.base = ldso.base;
1916 if (replace_argv0) argv[0] = replace_argv0;
1920 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1924 static void prepare_lazy(struct dso *p)
1926 size_t dyn[DYN_CNT], n, flags1=0;
1927 decode_vec(p->dynv, dyn, DYN_CNT);
1928 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1929 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1931 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1932 if (NEED_MIPS_GOT_RELOCS) {
1933 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1934 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1937 p->lazy = calloc(n, 3*sizeof(size_t));
1939 error("Error preparing lazy relocation for %s: %m", p->name);
1940 longjmp(*rtld_fail, 1);
1942 p->lazy_next = lazy_head;
1946 void *dlopen(const char *file, int mode)
1948 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1949 struct tls_module *orig_tls_tail;
1950 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1954 struct dso **volatile ctor_queue = 0;
1956 if (!file) return head;
1958 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1959 pthread_rwlock_wrlock(&lock);
1963 if (shutting_down) {
1964 error("Cannot dlopen while program is exiting.");
1967 orig_tls_tail = tls_tail;
1968 orig_tls_cnt = tls_cnt;
1969 orig_tls_offset = tls_offset;
1970 orig_tls_align = tls_align;
1971 orig_lazy_head = lazy_head;
1972 orig_syms_tail = syms_tail;
1974 noload = mode & RTLD_NOLOAD;
1977 if (setjmp(*rtld_fail)) {
1978 /* Clean up anything new that was (partially) loaded */
1979 revert_syms(orig_syms_tail);
1980 for (p=orig_tail->next; p; p=next) {
1982 while (p->td_index) {
1983 void *tmp = p->td_index->next;
1988 if (p->rpath != p->rpath_orig)
1995 if (!orig_tls_tail) libc.tls_head = 0;
1996 tls_tail = orig_tls_tail;
1997 if (tls_tail) tls_tail->next = 0;
1998 tls_cnt = orig_tls_cnt;
1999 tls_offset = orig_tls_offset;
2000 tls_align = orig_tls_align;
2001 lazy_head = orig_lazy_head;
2006 } else p = load_library(file, head);
2010 "Library %s is not already loaded" :
2011 "Error loading shared library %s: %m",
2016 /* First load handling */
2019 pthread_mutex_lock(&init_fini_lock);
2020 if (!p->constructed) ctor_queue = queue_ctors(p);
2021 pthread_mutex_unlock(&init_fini_lock);
2022 if (!p->relocated && (mode & RTLD_LAZY)) {
2024 for (i=0; p->deps[i]; i++)
2025 if (!p->deps[i]->relocated)
2026 prepare_lazy(p->deps[i]);
2028 if (!p->relocated || (mode & RTLD_GLOBAL)) {
2029 /* Make new symbols global, at least temporarily, so we can do
2030 * relocations. If not RTLD_GLOBAL, this is reverted below. */
2032 for (i=0; p->deps[i]; i++)
2033 add_syms(p->deps[i]);
2035 if (!p->relocated) {
2039 /* If RTLD_GLOBAL was not specified, undo any new additions
2040 * to the global symbol table. This is a nop if the library was
2041 * previously loaded and already global. */
2042 if (!(mode & RTLD_GLOBAL))
2043 revert_syms(orig_syms_tail);
2045 /* Processing of deferred lazy relocations must not happen until
2046 * the new libraries are committed; otherwise we could end up with
2047 * relocations resolved to symbol definitions that get removed. */
2051 if (tls_cnt != orig_tls_cnt)
2058 pthread_rwlock_unlock(&lock);
2060 do_init_fini(ctor_queue);
2063 pthread_setcancelstate(cs, 0);
2067 hidden int __dl_invalid_handle(void *h)
2070 for (p=head; p; p=p->next) if (h==p) return 0;
2071 error("Invalid library handle %p", (void *)h);
2075 static void *addr2dso(size_t a)
2079 if (DL_FDPIC) for (p=head; p; p=p->next) {
2081 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
2084 for (p=head; p; p=p->next) {
2085 if (DL_FDPIC && p->loadmap) {
2086 for (i=0; i<p->loadmap->nsegs; i++) {
2087 if (a-p->loadmap->segs[i].p_vaddr
2088 < p->loadmap->segs[i].p_memsz)
2093 size_t phcnt = p->phnum;
2094 size_t entsz = p->phentsize;
2095 size_t base = (size_t)p->base;
2096 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
2097 if (ph->p_type != PT_LOAD) continue;
2098 if (a-base-ph->p_vaddr < ph->p_memsz)
2101 if (a-(size_t)p->map < p->map_len)
2108 static void *do_dlsym(struct dso *p, const char *s, void *ra)
2111 uint32_t h = 0, gh = 0, *ght;
2113 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
2114 if (p == RTLD_DEFAULT) {
2116 } else if (p == RTLD_NEXT) {
2117 p = addr2dso((size_t)ra);
2121 struct symdef def = find_sym(p, s, 0);
2122 if (!def.sym) goto failed;
2123 if ((def.sym->st_info&0xf) == STT_TLS)
2124 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
2125 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
2126 return def.dso->funcdescs + (def.sym - def.dso->syms);
2127 return laddr(def.dso, def.sym->st_value);
2129 if (__dl_invalid_handle(p))
2131 if ((ght = p->ghashtab)) {
2133 sym = gnu_lookup(gh, ght, p, s);
2136 sym = sysv_lookup(s, h, p);
2138 if (sym && (sym->st_info&0xf) == STT_TLS)
2139 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
2140 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2141 return p->funcdescs + (sym - p->syms);
2142 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2143 return laddr(p, sym->st_value);
2144 for (i=0; p->deps[i]; i++) {
2145 if ((ght = p->deps[i]->ghashtab)) {
2146 if (!gh) gh = gnu_hash(s);
2147 sym = gnu_lookup(gh, ght, p->deps[i], s);
2149 if (!h) h = sysv_hash(s);
2150 sym = sysv_lookup(s, h, p->deps[i]);
2152 if (sym && (sym->st_info&0xf) == STT_TLS)
2153 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
2154 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2155 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
2156 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2157 return laddr(p->deps[i], sym->st_value);
2160 error("Symbol not found: %s", s);
2164 int dladdr(const void *addr_arg, Dl_info *info)
2166 size_t addr = (size_t)addr_arg;
2172 size_t besterr = -1;
2174 pthread_rwlock_rdlock(&lock);
2176 pthread_rwlock_unlock(&lock);
2181 strings = p->strings;
2182 nsym = count_syms(p);
2185 size_t idx = (addr-(size_t)p->funcdescs)
2186 / sizeof(*p->funcdescs);
2187 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2188 best = (size_t)(p->funcdescs + idx);
2189 bestsym = sym + idx;
2194 if (!best) for (; nsym; nsym--, sym++) {
2196 && (1<<(sym->st_info&0xf) & OK_TYPES)
2197 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2198 size_t symaddr = (size_t)laddr(p, sym->st_value);
2199 if (symaddr > addr || symaddr <= best)
2203 besterr = addr - symaddr;
2204 if (addr == symaddr)
2209 if (bestsym && besterr > bestsym->st_size-1) {
2214 info->dli_fname = p->name;
2215 info->dli_fbase = p->map;
2218 info->dli_sname = 0;
2219 info->dli_saddr = 0;
2223 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2224 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2225 info->dli_sname = strings + bestsym->st_name;
2226 info->dli_saddr = (void *)best;
2231 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2234 pthread_rwlock_rdlock(&lock);
2235 res = do_dlsym(p, s, ra);
2236 pthread_rwlock_unlock(&lock);
2240 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2242 struct dso *current;
2243 struct dl_phdr_info info;
2245 for(current = head; current;) {
2246 info.dlpi_addr = (uintptr_t)current->base;
2247 info.dlpi_name = current->name;
2248 info.dlpi_phdr = current->phdr;
2249 info.dlpi_phnum = current->phnum;
2250 info.dlpi_adds = gencnt;
2252 info.dlpi_tls_modid = current->tls_id;
2253 info.dlpi_tls_data = current->tls.image;
2255 ret = (callback)(&info, sizeof (info), data);
2257 if (ret != 0) break;
2259 pthread_rwlock_rdlock(&lock);
2260 current = current->next;
2261 pthread_rwlock_unlock(&lock);
2266 static void error(const char *fmt, ...)
2271 vdprintf(2, fmt, ap);
2277 __dl_vseterr(fmt, ap);