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;
74 struct dso **deps, *needed_by;
75 char *rpath_orig, *rpath;
76 struct tls_module tls;
78 size_t relro_start, relro_end;
80 unsigned char *new_tls;
81 volatile int new_dtv_idx, new_tls_idx;
82 struct td_index *td_index;
83 struct dso *fini_next;
88 struct fdpic_loadmap *loadmap;
103 static struct builtin_tls {
108 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
110 #define ADDEND_LIMIT 4096
111 static size_t *saved_addends, *apply_addends_to;
113 static struct dso ldso;
114 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
115 static char *env_path, *sys_path;
116 static unsigned long long gencnt;
119 static int ldso_fail;
121 static jmp_buf *rtld_fail;
122 static pthread_rwlock_t lock;
123 static struct debug debug;
124 static struct tls_module *tls_tail;
125 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
126 static size_t static_tls_cnt;
127 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
128 static struct fdpic_loadmap *app_loadmap;
129 static struct fdpic_dummy_loadmap app_dummy_loadmap;
130 static struct dso *const nodeps_dummy;
132 struct debug *_dl_debug_addr = &debug;
134 extern hidden int __malloc_replaced;
136 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
138 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
140 weak_alias(__init_array_start, __init_array_end);
141 weak_alias(__fini_array_start, __fini_array_end);
143 static int dl_strcmp(const char *l, const char *r)
145 for (; *l==*r && *l; l++, r++);
146 return *(unsigned char *)l - *(unsigned char *)r;
148 #define strcmp(l,r) dl_strcmp(l,r)
150 /* Compute load address for a virtual address in a given dso. */
152 static void *laddr(const struct dso *p, size_t v)
155 if (!p->loadmap) return p->base + v;
156 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
157 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
159 static void *laddr_pg(const struct dso *p, size_t v)
162 size_t pgsz = PAGE_SIZE;
163 if (!p->loadmap) return p->base + v;
165 size_t a = p->loadmap->segs[j].p_vaddr;
166 size_t b = a + p->loadmap->segs[j].p_memsz;
172 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
174 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
175 laddr(p, v), (p)->got })
177 #define laddr(p, v) (void *)((p)->base + (v))
178 #define laddr_pg(p, v) laddr(p, v)
179 #define fpaddr(p, v) ((void (*)())laddr(p, v))
182 static void decode_vec(size_t *v, size_t *a, size_t cnt)
185 for (i=0; i<cnt; i++) a[i] = 0;
186 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
192 static int search_vec(size_t *v, size_t *r, size_t key)
194 for (; v[0]!=key; v+=2)
200 static uint32_t sysv_hash(const char *s0)
202 const unsigned char *s = (void *)s0;
208 return h & 0xfffffff;
211 static uint32_t gnu_hash(const char *s0)
213 const unsigned char *s = (void *)s0;
214 uint_fast32_t h = 5381;
220 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
223 Sym *syms = dso->syms;
224 Elf_Symndx *hashtab = dso->hashtab;
225 char *strings = dso->strings;
226 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
227 if ((!dso->versym || dso->versym[i] >= 0)
228 && (!strcmp(s, strings+syms[i].st_name)))
234 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
236 uint32_t nbuckets = hashtab[0];
237 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
238 uint32_t i = buckets[h1 % nbuckets];
242 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
244 for (h1 |= 1; ; i++) {
245 uint32_t h2 = *hashval++;
246 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
247 && !strcmp(s, dso->strings + dso->syms[i].st_name))
255 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
257 const size_t *bloomwords = (const void *)(hashtab+4);
258 size_t f = bloomwords[fofs & (hashtab[2]-1)];
259 if (!(f & fmask)) return 0;
261 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
262 if (!(f & 1)) return 0;
264 return gnu_lookup(h1, hashtab, dso, s);
267 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
268 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
270 #ifndef ARCH_SYM_REJECT_UND
271 #define ARCH_SYM_REJECT_UND(s) 0
274 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
276 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
277 size_t ghm = 1ul << gh % (8*sizeof(size_t));
278 struct symdef def = {0};
279 for (; dso; dso=dso->syms_next) {
281 if ((ght = dso->ghashtab)) {
282 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
284 if (!h) h = sysv_hash(s);
285 sym = sysv_lookup(s, h, dso);
289 if (need_def || (sym->st_info&0xf) == STT_TLS
290 || ARCH_SYM_REJECT_UND(sym))
293 if ((sym->st_info&0xf) != STT_TLS)
295 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
296 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
304 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
306 unsigned char *base = dso->base;
307 Sym *syms = dso->syms;
308 char *strings = dso->strings;
319 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
322 /* Only ldso's REL table needs addend saving/reuse. */
323 if (rel == apply_addends_to)
328 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
329 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
330 type = R_TYPE(rel[1]);
331 if (type == REL_NONE) continue;
332 reloc_addr = laddr(dso, rel[0]);
336 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
338 } else if (reuse_addends) {
339 /* Save original addend in stage 2 where the dso
340 * chain consists of just ldso; otherwise read back
341 * saved addend since the inline one was clobbered. */
343 saved_addends[save_slot] = *reloc_addr;
344 addend = saved_addends[save_slot++];
346 addend = *reloc_addr;
349 sym_index = R_SYM(rel[1]);
351 sym = syms + sym_index;
352 name = strings + sym->st_name;
353 ctx = type==REL_COPY ? head->syms_next : head;
354 def = (sym->st_info&0xf) == STT_SECTION
355 ? (struct symdef){ .dso = dso, .sym = sym }
356 : find_sym(ctx, name, type==REL_PLT);
357 if (!def.sym && (sym->st_shndx != SHN_UNDEF
358 || sym->st_info>>4 != STB_WEAK)) {
359 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
360 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
361 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
362 dso->lazy[3*dso->lazy_cnt+2] = addend;
366 error("Error relocating %s: %s: symbol not found",
368 if (runtime) longjmp(*rtld_fail, 1);
377 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
378 tls_val = def.sym ? def.sym->st_value : 0;
380 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
381 && runtime && def.dso->tls_id > static_tls_cnt) {
382 error("Error relocating %s: %s: initial-exec TLS "
383 "resolves to dynamic definition in %s",
384 dso->name, name, def.dso->name);
385 longjmp(*rtld_fail, 1);
392 addend -= (size_t)reloc_addr;
396 *reloc_addr = sym_val + addend;
399 *reloc_addr = (size_t)base + addend;
402 if (sym) *reloc_addr = sym_val + addend;
403 else *reloc_addr = (size_t)base + addend;
406 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
409 *(uint32_t *)reloc_addr = sym_val + addend
410 - (size_t)reloc_addr;
413 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
414 + (def.sym - def.dso->syms)) : 0;
416 case REL_FUNCDESC_VAL:
417 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
418 else *reloc_addr = sym_val;
419 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
422 *reloc_addr = def.dso->tls_id;
425 *reloc_addr = tls_val + addend - DTP_OFFSET;
429 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
433 *reloc_addr = tls_val - def.dso->tls.offset + addend;
436 *reloc_addr = def.dso->tls.offset - tls_val + addend;
440 if (stride<3) addend = reloc_addr[1];
441 if (runtime && def.dso->tls_id > static_tls_cnt) {
442 struct td_index *new = malloc(sizeof *new);
445 "Error relocating %s: cannot allocate TLSDESC for %s",
446 dso->name, sym ? name : "(local)" );
447 longjmp(*rtld_fail, 1);
449 new->next = dso->td_index;
451 new->args[0] = def.dso->tls_id;
452 new->args[1] = tls_val + addend - DTP_OFFSET;
453 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
454 reloc_addr[1] = (size_t)new;
456 reloc_addr[0] = (size_t)__tlsdesc_static;
458 reloc_addr[1] = tls_val + def.dso->tls.offset
461 reloc_addr[1] = tls_val - def.dso->tls.offset
465 #ifdef TLSDESC_BACKWARDS
466 /* Some archs (32-bit ARM at least) invert the order of
467 * the descriptor members. Fix them up here. */
468 size_t tmp = reloc_addr[0];
469 reloc_addr[0] = reloc_addr[1];
474 error("Error relocating %s: unsupported relocation type %d",
476 if (runtime) longjmp(*rtld_fail, 1);
482 static void redo_lazy_relocs()
484 struct dso *p = lazy_head, *next;
488 size_t size = p->lazy_cnt*3*sizeof(size_t);
490 do_relocs(p, p->lazy, size, 3);
492 p->lazy_next = lazy_head;
502 /* A huge hack: to make up for the wastefulness of shared libraries
503 * needing at least a page of dirty memory even if they have no global
504 * data, we reclaim the gaps at the beginning and end of writable maps
505 * and "donate" them to the heap. */
507 static void reclaim(struct dso *dso, size_t start, size_t end)
509 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
510 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
511 if (start >= end) return;
512 char *base = laddr_pg(dso, start);
513 __malloc_donate(base, base+(end-start));
516 static void reclaim_gaps(struct dso *dso)
518 Phdr *ph = dso->phdr;
519 size_t phcnt = dso->phnum;
521 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
522 if (ph->p_type!=PT_LOAD) continue;
523 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
524 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
525 reclaim(dso, ph->p_vaddr+ph->p_memsz,
526 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
530 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
532 static int no_map_fixed;
535 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
536 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
540 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
541 if (flags & MAP_ANONYMOUS) {
546 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
547 for (q=p; n; q+=r, off+=r, n-=r) {
549 if (r < 0 && errno != EINTR) return MAP_FAILED;
558 static void unmap_library(struct dso *dso)
562 for (i=0; i<dso->loadmap->nsegs; i++) {
563 if (!dso->loadmap->segs[i].p_memsz)
565 munmap((void *)dso->loadmap->segs[i].addr,
566 dso->loadmap->segs[i].p_memsz);
569 } else if (dso->map && dso->map_len) {
570 munmap(dso->map, dso->map_len);
574 static void *map_library(int fd, struct dso *dso)
576 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
577 void *allocated_buf=0;
579 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
580 size_t this_min, this_max;
586 unsigned char *map=MAP_FAILED, *base;
591 ssize_t l = read(fd, buf, sizeof buf);
594 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
596 phsize = eh->e_phentsize * eh->e_phnum;
597 if (phsize > sizeof buf - sizeof *eh) {
598 allocated_buf = malloc(phsize);
599 if (!allocated_buf) return 0;
600 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
601 if (l < 0) goto error;
602 if (l != phsize) goto noexec;
603 ph = ph0 = allocated_buf;
604 } else if (eh->e_phoff + phsize > l) {
605 l = pread(fd, buf+1, phsize, eh->e_phoff);
606 if (l < 0) goto error;
607 if (l != phsize) goto noexec;
608 ph = ph0 = (void *)(buf + 1);
610 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
612 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
613 if (ph->p_type == PT_DYNAMIC) {
615 } else if (ph->p_type == PT_TLS) {
616 tls_image = ph->p_vaddr;
617 dso->tls.align = ph->p_align;
618 dso->tls.len = ph->p_filesz;
619 dso->tls.size = ph->p_memsz;
620 } else if (ph->p_type == PT_GNU_RELRO) {
621 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
622 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
623 } else if (ph->p_type == PT_GNU_STACK) {
624 if (!runtime && ph->p_memsz > __default_stacksize) {
625 __default_stacksize =
626 ph->p_memsz < DEFAULT_STACK_MAX ?
627 ph->p_memsz : DEFAULT_STACK_MAX;
630 if (ph->p_type != PT_LOAD) continue;
632 if (ph->p_vaddr < addr_min) {
633 addr_min = ph->p_vaddr;
634 off_start = ph->p_offset;
635 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
636 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
637 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
639 if (ph->p_vaddr+ph->p_memsz > addr_max) {
640 addr_max = ph->p_vaddr+ph->p_memsz;
643 if (!dyn) goto noexec;
644 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
645 dso->loadmap = calloc(1, sizeof *dso->loadmap
646 + nsegs * sizeof *dso->loadmap->segs);
647 if (!dso->loadmap) goto error;
648 dso->loadmap->nsegs = nsegs;
649 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
650 if (ph->p_type != PT_LOAD) continue;
651 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
652 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
653 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
654 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
656 fd, ph->p_offset & -PAGE_SIZE);
657 if (map == MAP_FAILED) {
661 dso->loadmap->segs[i].addr = (size_t)map +
662 (ph->p_vaddr & PAGE_SIZE-1);
663 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
664 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
666 if (prot & PROT_WRITE) {
667 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
669 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
670 size_t pgend = brk + ph->p_memsz - ph->p_filesz
671 + PAGE_SIZE-1 & -PAGE_SIZE;
672 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
674 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
675 -1, off_start) == MAP_FAILED)
677 memset(map + brk, 0, pgbrk-brk);
680 map = (void *)dso->loadmap->segs[0].addr;
684 addr_max += PAGE_SIZE-1;
685 addr_max &= -PAGE_SIZE;
686 addr_min &= -PAGE_SIZE;
687 off_start &= -PAGE_SIZE;
688 map_len = addr_max - addr_min + off_start;
689 /* The first time, we map too much, possibly even more than
690 * the length of the file. This is okay because we will not
691 * use the invalid part; we just need to reserve the right
692 * amount of virtual address space to map over later. */
693 map = DL_NOMMU_SUPPORT
694 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
695 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
696 : mmap((void *)addr_min, map_len, prot,
697 MAP_PRIVATE, fd, off_start);
698 if (map==MAP_FAILED) goto error;
700 dso->map_len = map_len;
701 /* If the loaded file is not relocatable and the requested address is
702 * not available, then the load operation must fail. */
703 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
707 base = map - addr_min;
710 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
711 if (ph->p_type != PT_LOAD) continue;
712 /* Check if the programs headers are in this load segment, and
713 * if so, record the address for use by dl_iterate_phdr. */
714 if (!dso->phdr && eh->e_phoff >= ph->p_offset
715 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
716 dso->phdr = (void *)(base + ph->p_vaddr
717 + (eh->e_phoff-ph->p_offset));
718 dso->phnum = eh->e_phnum;
719 dso->phentsize = eh->e_phentsize;
721 this_min = ph->p_vaddr & -PAGE_SIZE;
722 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
723 off_start = ph->p_offset & -PAGE_SIZE;
724 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
725 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
726 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
727 /* Reuse the existing mapping for the lowest-address LOAD */
728 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
729 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
731 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
732 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
733 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
734 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
735 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)
739 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
740 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
741 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
748 dso->dynv = laddr(dso, dyn);
749 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
755 if (map!=MAP_FAILED) unmap_library(dso);
760 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
765 s += strspn(s, ":\n");
766 l = strcspn(s, ":\n");
767 if (l-1 >= INT_MAX) return -1;
768 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
769 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
777 /* Any negative value but -1 will inhibit
778 * futher path search. */
786 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
789 const char *s, *t, *origin;
791 if (p->rpath || !p->rpath_orig) return 0;
792 if (!strchr(p->rpath_orig, '$')) {
793 p->rpath = p->rpath_orig;
798 while ((t=strchr(s, '$'))) {
799 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
804 if (n > SSIZE_MAX/PATH_MAX) return 0;
806 if (p->kernel_mapped) {
807 /* $ORIGIN searches cannot be performed for the main program
808 * when it is suid/sgid/AT_SECURE. This is because the
809 * pathname is under the control of the caller of execve.
810 * For libraries, however, $ORIGIN can be processed safely
811 * since the library's pathname came from a trusted source
812 * (either system paths or a call to dlopen). */
815 l = readlink("/proc/self/exe", buf, buf_size);
816 if (l == -1) switch (errno) {
831 t = strrchr(origin, '/');
835 /* Normally p->name will always be an absolute or relative
836 * pathname containing at least one '/' character, but in the
837 * case where ldso was invoked as a command to execute a
838 * program in the working directory, app.name may not. Fix. */
842 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
843 if (libc.secure && *origin != '/')
845 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
846 if (!p->rpath) return -1;
850 while ((t=strchr(s, '$'))) {
853 memcpy(d, origin, l);
855 /* It was determined previously that the '$' is followed
856 * either by "ORIGIN" or "{ORIGIN}". */
857 s = t + 7 + 2*(t[1]=='{');
863 static void decode_dyn(struct dso *p)
866 decode_vec(p->dynv, dyn, DYN_CNT);
867 p->syms = laddr(p, dyn[DT_SYMTAB]);
868 p->strings = laddr(p, dyn[DT_STRTAB]);
869 if (dyn[0]&(1<<DT_HASH))
870 p->hashtab = laddr(p, dyn[DT_HASH]);
871 if (dyn[0]&(1<<DT_RPATH))
872 p->rpath_orig = p->strings + dyn[DT_RPATH];
873 if (dyn[0]&(1<<DT_RUNPATH))
874 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
875 if (dyn[0]&(1<<DT_PLTGOT))
876 p->got = laddr(p, dyn[DT_PLTGOT]);
877 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
878 p->ghashtab = laddr(p, *dyn);
879 if (search_vec(p->dynv, dyn, DT_VERSYM))
880 p->versym = laddr(p, *dyn);
883 static size_t count_syms(struct dso *p)
885 if (p->hashtab) return p->hashtab[1];
888 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
890 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
891 if (buckets[i] > nsym)
895 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
897 while (!(*hashval++ & 1));
902 static void *dl_mmap(size_t n)
905 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
907 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
909 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
911 return p == MAP_FAILED ? 0 : p;
914 static void makefuncdescs(struct dso *p)
916 static int self_done;
917 size_t nsym = count_syms(p);
918 size_t i, size = nsym * sizeof(*p->funcdescs);
921 p->funcdescs = dl_mmap(size);
924 p->funcdescs = malloc(size);
927 if (!runtime) a_crash();
928 error("Error allocating function descriptors for %s", p->name);
929 longjmp(*rtld_fail, 1);
931 for (i=0; i<nsym; i++) {
932 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
933 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
934 p->funcdescs[i].got = p->got;
936 p->funcdescs[i].addr = 0;
937 p->funcdescs[i].got = 0;
942 static struct dso *load_library(const char *name, struct dso *needed_by)
944 char buf[2*NAME_MAX+2];
945 const char *pathname;
947 struct dso *p, temp_dso = {0};
959 /* Catch and block attempts to reload the implementation itself */
960 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
961 static const char reserved[] =
962 "c.pthread.rt.m.dl.util.xnet.";
963 const char *rp, *next;
964 for (rp=reserved; *rp; rp=next) {
965 next = strchr(rp, '.') + 1;
966 if (strncmp(name+3, rp, next-rp) == 0)
971 /* Track which names have been resolved
972 * and only report each one once. */
973 static unsigned reported;
974 unsigned mask = 1U<<(rp-reserved);
975 if (!(reported & mask)) {
977 dprintf(1, "\t%s => %s (%p)\n",
985 if (!strcmp(name, ldso.name)) is_self = 1;
994 if (strchr(name, '/')) {
996 fd = open(name, O_RDONLY|O_CLOEXEC);
998 /* Search for the name to see if it's already loaded */
999 for (p=head->next; p; p=p->next) {
1000 if (p->shortname && !strcmp(p->shortname, name)) {
1004 if (strlen(name) > NAME_MAX) return 0;
1006 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1007 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1008 if (fixup_rpath(p, buf, sizeof buf) < 0)
1009 fd = -2; /* Inhibit further search. */
1011 fd = path_open(name, p->rpath, buf, sizeof buf);
1017 if (ldso.name[0]=='/') {
1019 for (s=t=z=ldso.name; *s; s++)
1020 if (*s=='/') z=t, t=s;
1021 prefix_len = z-ldso.name;
1022 if (prefix_len < PATH_MAX)
1029 char etc_ldso_path[prefix_len + 1
1030 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1031 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1032 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1033 (int)prefix_len, prefix);
1034 FILE *f = fopen(etc_ldso_path, "rbe");
1036 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1041 } else if (errno != ENOENT) {
1045 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1046 fd = path_open(name, sys_path, buf, sizeof buf);
1050 if (fd < 0) return 0;
1051 if (fstat(fd, &st) < 0) {
1055 for (p=head->next; p; p=p->next) {
1056 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1057 /* If this library was previously loaded with a
1058 * pathname but a search found the same inode,
1059 * setup its shortname so it can be found by name. */
1060 if (!p->shortname && pathname != name)
1061 p->shortname = strrchr(p->name, '/')+1;
1066 map = noload ? 0 : map_library(fd, &temp_dso);
1070 /* Avoid the danger of getting two versions of libc mapped into the
1071 * same process when an absolute pathname was used. The symbols
1072 * checked are chosen to catch both musl and glibc, and to avoid
1073 * false positives from interposition-hack libraries. */
1074 decode_dyn(&temp_dso);
1075 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1076 find_sym(&temp_dso, "stdin", 1).sym) {
1077 unmap_library(&temp_dso);
1078 return load_library("libc.so", needed_by);
1080 /* Past this point, if we haven't reached runtime yet, ldso has
1081 * committed either to use the mapped library or to abort execution.
1082 * Unmapping is not possible, so we can safely reclaim gaps. */
1083 if (!runtime) reclaim_gaps(&temp_dso);
1085 /* Allocate storage for the new DSO. When there is TLS, this
1086 * storage must include a reservation for all pre-existing
1087 * threads to obtain copies of both the new TLS, and an
1088 * extended DTV capable of storing an additional slot for
1089 * the newly-loaded DSO. */
1090 alloc_size = sizeof *p + strlen(pathname) + 1;
1091 if (runtime && temp_dso.tls.image) {
1092 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1093 + sizeof(void *) * (tls_cnt+3);
1094 n_th = libc.threads_minus_1 + 1;
1095 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1096 else alloc_size += n_th * per_th;
1098 p = calloc(1, alloc_size);
1100 unmap_library(&temp_dso);
1103 memcpy(p, &temp_dso, sizeof temp_dso);
1106 p->needed_by = needed_by;
1108 strcpy(p->name, pathname);
1109 /* Add a shortname only if name arg was not an explicit pathname. */
1110 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1112 p->tls_id = ++tls_cnt;
1113 tls_align = MAXP2(tls_align, p->tls.align);
1115 p->tls.offset = tls_offset + ( (tls_align-1) &
1116 -(tls_offset + (uintptr_t)p->tls.image) );
1117 tls_offset += p->tls.size;
1119 tls_offset += p->tls.size + p->tls.align - 1;
1120 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1122 p->tls.offset = tls_offset;
1124 p->new_dtv = (void *)(-sizeof(size_t) &
1125 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1126 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1127 if (tls_tail) tls_tail->next = &p->tls;
1128 else libc.tls_head = &p->tls;
1136 if (DL_FDPIC) makefuncdescs(p);
1138 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1143 static void load_deps(struct dso *p)
1146 struct dso ***deps = &p->deps, **tmp, *dep;
1147 for (; p; p=p->next) {
1148 for (i=0; p->dynv[i]; i+=2) {
1149 if (p->dynv[i] != DT_NEEDED) continue;
1150 dep = load_library(p->strings + p->dynv[i+1], p);
1152 error("Error loading shared library %s: %m (needed by %s)",
1153 p->strings + p->dynv[i+1], p->name);
1154 if (runtime) longjmp(*rtld_fail, 1);
1158 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
1159 if (!tmp) longjmp(*rtld_fail, 1);
1166 if (!*deps) *deps = (struct dso **)&nodeps_dummy;
1169 static void load_preload(char *s)
1173 for (z=s; *z; s=z) {
1174 for ( ; *s && (isspace(*s) || *s==':'); s++);
1175 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1183 static void add_syms(struct dso *p)
1185 if (!p->syms_next && syms_tail != p) {
1186 syms_tail->syms_next = p;
1191 static void revert_syms(struct dso *old_tail)
1193 struct dso *p, *next;
1194 /* Chop off the tail of the list of dsos that participate in
1195 * the global symbol table, reverting them to RTLD_LOCAL. */
1196 for (p=old_tail; p; p=next) {
1197 next = p->syms_next;
1200 syms_tail = old_tail;
1203 static void do_mips_relocs(struct dso *p, size_t *got)
1205 size_t i, j, rel[2];
1206 unsigned char *base = p->base;
1207 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1211 while (i--) *got++ += (size_t)base;
1213 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1214 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1215 Sym *sym = p->syms + j;
1216 rel[0] = (unsigned char *)got - base;
1217 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1218 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1219 do_relocs(p, rel, sizeof rel, 2);
1223 static void reloc_all(struct dso *p)
1225 size_t dyn[DYN_CNT];
1226 for (; p; p=p->next) {
1227 if (p->relocated) continue;
1228 decode_vec(p->dynv, dyn, DYN_CNT);
1229 if (NEED_MIPS_GOT_RELOCS)
1230 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1231 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1232 2+(dyn[DT_PLTREL]==DT_RELA));
1233 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1234 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1236 if (head != &ldso && p->relro_start != p->relro_end &&
1237 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1238 && errno != ENOSYS) {
1239 error("Error relocating %s: RELRO protection failed: %m",
1241 if (runtime) longjmp(*rtld_fail, 1);
1248 static void kernel_mapped_dso(struct dso *p)
1250 size_t min_addr = -1, max_addr = 0, cnt;
1252 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1253 if (ph->p_type == PT_DYNAMIC) {
1254 p->dynv = laddr(p, ph->p_vaddr);
1255 } else if (ph->p_type == PT_GNU_RELRO) {
1256 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1257 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1258 } else if (ph->p_type == PT_GNU_STACK) {
1259 if (!runtime && ph->p_memsz > __default_stacksize) {
1260 __default_stacksize =
1261 ph->p_memsz < DEFAULT_STACK_MAX ?
1262 ph->p_memsz : DEFAULT_STACK_MAX;
1265 if (ph->p_type != PT_LOAD) continue;
1266 if (ph->p_vaddr < min_addr)
1267 min_addr = ph->p_vaddr;
1268 if (ph->p_vaddr+ph->p_memsz > max_addr)
1269 max_addr = ph->p_vaddr+ph->p_memsz;
1271 min_addr &= -PAGE_SIZE;
1272 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1273 p->map = p->base + min_addr;
1274 p->map_len = max_addr - min_addr;
1275 p->kernel_mapped = 1;
1278 void __libc_exit_fini()
1281 size_t dyn[DYN_CNT];
1282 for (p=fini_head; p; p=p->fini_next) {
1283 if (!p->constructed) continue;
1284 decode_vec(p->dynv, dyn, DYN_CNT);
1285 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1286 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1287 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1288 while (n--) ((void (*)(void))*--fn)();
1290 #ifndef NO_LEGACY_INITFINI
1291 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1292 fpaddr(p, dyn[DT_FINI])();
1297 static void do_init_fini(struct dso *p)
1299 size_t dyn[DYN_CNT];
1300 int need_locking = libc.threads_minus_1;
1301 /* Allow recursive calls that arise when a library calls
1302 * dlopen from one of its constructors, but block any
1303 * other threads until all ctors have finished. */
1304 if (need_locking) pthread_mutex_lock(&init_fini_lock);
1305 for (; p; p=p->prev) {
1306 if (p->constructed) continue;
1308 decode_vec(p->dynv, dyn, DYN_CNT);
1309 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1310 p->fini_next = fini_head;
1313 #ifndef NO_LEGACY_INITFINI
1314 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1315 fpaddr(p, dyn[DT_INIT])();
1317 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1318 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1319 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1320 while (n--) ((void (*)(void))*fn++)();
1322 if (!need_locking && libc.threads_minus_1) {
1324 pthread_mutex_lock(&init_fini_lock);
1327 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1330 void __libc_start_init(void)
1335 static void dl_debug_state(void)
1339 weak_alias(dl_debug_state, _dl_debug_state);
1341 void __init_tls(size_t *auxv)
1345 static void update_tls_size()
1347 libc.tls_cnt = tls_cnt;
1348 libc.tls_align = tls_align;
1349 libc.tls_size = ALIGN(
1350 (1+tls_cnt) * sizeof(void *) +
1352 sizeof(struct pthread) +
1357 static void install_new_tls(void)
1360 pthread_t self = __pthread_self(), td;
1361 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1362 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1365 size_t old_cnt = self->dtv[0];
1367 __block_app_sigs(&set);
1369 /* Copy existing dtv contents from all existing threads. */
1370 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1371 memcpy(newdtv+i, td->dtv,
1372 (old_cnt+1)*sizeof(uintptr_t));
1373 newdtv[i][0] = tls_cnt;
1375 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1376 for (p=head; ; p=p->next) {
1377 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1378 unsigned char *mem = p->new_tls;
1379 for (j=0; j<i; j++) {
1380 unsigned char *new = mem;
1381 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1383 memcpy(new, p->tls.image, p->tls.len);
1384 newdtv[j][p->tls_id] =
1385 (uintptr_t)new + DTP_OFFSET;
1386 mem += p->tls.size + p->tls.align;
1388 if (p->tls_id == tls_cnt) break;
1391 /* Broadcast barrier to ensure contents of new dtv is visible
1392 * if the new dtv pointer is. The __membarrier function has a
1393 * fallback emulation using signals for kernels that lack the
1394 * feature at the syscall level. */
1396 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1398 /* Install new dtv for each thread. */
1399 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1400 td->dtv = td->dtv_copy = newdtv[j];
1404 __restore_sigs(&set);
1407 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1408 * following stage 2 and stage 3 functions via primitive symbolic lookup
1409 * since it does not have access to their addresses to begin with. */
1411 /* Stage 2 of the dynamic linker is called after relative relocations
1412 * have been processed. It can make function calls to static functions
1413 * and access string literals and static data, but cannot use extern
1414 * symbols. Its job is to perform symbolic relocations on the dynamic
1415 * linker itself, but some of the relocations performed may need to be
1416 * replaced later due to copy relocations in the main program. */
1418 hidden void __dls2(unsigned char *base, size_t *sp)
1421 void *p1 = (void *)sp[-2];
1422 void *p2 = (void *)sp[-1];
1424 size_t *auxv, aux[AUX_CNT];
1425 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1427 decode_vec(auxv, aux, AUX_CNT);
1428 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1429 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1431 app_loadmap = p2 ? p1 : 0;
1432 ldso.loadmap = p2 ? p2 : p1;
1433 ldso.base = laddr(&ldso, 0);
1437 Ehdr *ehdr = (void *)ldso.base;
1438 ldso.name = ldso.shortname = "libc.so";
1439 ldso.phnum = ehdr->e_phnum;
1440 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1441 ldso.phentsize = ehdr->e_phentsize;
1442 kernel_mapped_dso(&ldso);
1445 if (DL_FDPIC) makefuncdescs(&ldso);
1447 /* Prepare storage for to save clobbered REL addends so they
1448 * can be reused in stage 3. There should be very few. If
1449 * something goes wrong and there are a huge number, abort
1450 * instead of risking stack overflow. */
1451 size_t dyn[DYN_CNT];
1452 decode_vec(ldso.dynv, dyn, DYN_CNT);
1453 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1454 size_t rel_size = dyn[DT_RELSZ];
1455 size_t symbolic_rel_cnt = 0;
1456 apply_addends_to = rel;
1457 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1458 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1459 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1460 size_t addends[symbolic_rel_cnt+1];
1461 saved_addends = addends;
1468 /* Call dynamic linker stage-2b, __dls2b, looking it up
1469 * symbolically as a barrier against moving the address
1470 * load across the above relocation processing. */
1471 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1472 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
1473 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
1476 /* Stage 2b sets up a valid thread pointer, which requires relocations
1477 * completed in stage 2, and on which stage 3 is permitted to depend.
1478 * This is done as a separate stage, with symbolic lookup as a barrier,
1479 * so that loads of the thread pointer and &errno can be pure/const and
1480 * thereby hoistable. */
1482 _Noreturn void __dls2b(size_t *sp)
1484 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1485 * use during dynamic linking. If possible it will also serve as the
1486 * thread pointer at runtime. */
1487 libc.tls_size = sizeof builtin_tls;
1488 libc.tls_align = tls_align;
1489 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1493 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1494 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1495 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1498 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1499 * fully functional. Its job is to load (if not already loaded) and
1500 * process dependencies and relocations for the main application and
1501 * transfer control to its entry point. */
1503 _Noreturn void __dls3(size_t *sp)
1505 static struct dso app, vdso;
1506 size_t aux[AUX_CNT], *auxv;
1508 char *env_preload=0;
1509 char *replace_argv0=0;
1512 char **argv = (void *)(sp+1);
1513 char **argv_orig = argv;
1514 char **envp = argv+argc+1;
1516 /* Find aux vector just past environ[] and use it to initialize
1517 * global data that may be needed before we can make syscalls. */
1519 for (i=argc+1; argv[i]; i++);
1520 libc.auxv = auxv = (void *)(argv+i+1);
1521 decode_vec(auxv, aux, AUX_CNT);
1522 __hwcap = aux[AT_HWCAP];
1523 libc.page_size = aux[AT_PAGESZ];
1524 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1525 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1527 /* Only trust user/env if kernel says we're not suid/sgid */
1529 env_path = getenv("LD_LIBRARY_PATH");
1530 env_preload = getenv("LD_PRELOAD");
1533 /* If the main program was already loaded by the kernel,
1534 * AT_PHDR will point to some location other than the dynamic
1535 * linker's program headers. */
1536 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1537 size_t interp_off = 0;
1538 size_t tls_image = 0;
1539 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1540 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1541 app.phnum = aux[AT_PHNUM];
1542 app.phentsize = aux[AT_PHENT];
1543 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1544 if (phdr->p_type == PT_PHDR)
1545 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1546 else if (phdr->p_type == PT_INTERP)
1547 interp_off = (size_t)phdr->p_vaddr;
1548 else if (phdr->p_type == PT_TLS) {
1549 tls_image = phdr->p_vaddr;
1550 app.tls.len = phdr->p_filesz;
1551 app.tls.size = phdr->p_memsz;
1552 app.tls.align = phdr->p_align;
1555 if (DL_FDPIC) app.loadmap = app_loadmap;
1556 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1557 if (interp_off) ldso.name = laddr(&app, interp_off);
1558 if ((aux[0] & (1UL<<AT_EXECFN))
1559 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1560 app.name = (char *)aux[AT_EXECFN];
1563 kernel_mapped_dso(&app);
1566 char *ldname = argv[0];
1567 size_t l = strlen(ldname);
1568 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1570 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1571 char *opt = argv[0]+2;
1572 *argv++ = (void *)-1;
1575 } else if (!memcmp(opt, "list", 5)) {
1577 } else if (!memcmp(opt, "library-path", 12)) {
1578 if (opt[12]=='=') env_path = opt+13;
1579 else if (opt[12]) *argv = 0;
1580 else if (*argv) env_path = *argv++;
1581 } else if (!memcmp(opt, "preload", 7)) {
1582 if (opt[7]=='=') env_preload = opt+8;
1583 else if (opt[7]) *argv = 0;
1584 else if (*argv) env_preload = *argv++;
1585 } else if (!memcmp(opt, "argv0", 5)) {
1586 if (opt[5]=='=') replace_argv0 = opt+6;
1587 else if (opt[5]) *argv = 0;
1588 else if (*argv) replace_argv0 = *argv++;
1593 argv[-1] = (void *)(argc - (argv-argv_orig));
1595 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1597 "Dynamic Program Loader\n"
1598 "Usage: %s [options] [--] pathname%s\n",
1599 __libc_version, ldname,
1600 ldd_mode ? "" : " [args]");
1603 fd = open(argv[0], O_RDONLY);
1605 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1608 Ehdr *ehdr = (void *)map_library(fd, &app);
1610 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1616 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1617 /* Find the name that would have been used for the dynamic
1618 * linker had ldd not taken its place. */
1620 for (i=0; i<app.phnum; i++) {
1621 if (app.phdr[i].p_type == PT_INTERP)
1622 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1624 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1628 libc.tls_head = tls_tail = &app.tls;
1629 app.tls_id = tls_cnt = 1;
1631 app.tls.offset = GAP_ABOVE_TP;
1632 app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
1633 tls_offset = app.tls.offset + app.tls.size
1634 + ( -((uintptr_t)app.tls.image + app.tls.size)
1635 & (app.tls.align-1) );
1637 tls_offset = app.tls.offset = app.tls.size
1638 + ( -((uintptr_t)app.tls.image + app.tls.size)
1639 & (app.tls.align-1) );
1641 tls_align = MAXP2(tls_align, app.tls.align);
1645 makefuncdescs(&app);
1647 app.loadmap = (void *)&app_dummy_loadmap;
1648 app.loadmap->nsegs = 1;
1649 app.loadmap->segs[0].addr = (size_t)app.map;
1650 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1652 app.loadmap->segs[0].p_memsz = app.map_len;
1654 argv[-3] = (void *)app.loadmap;
1657 /* Initial dso chain consists only of the app. */
1658 head = tail = syms_tail = &app;
1660 /* Donate unused parts of app and library mapping to malloc */
1662 reclaim_gaps(&ldso);
1664 /* Load preload/needed libraries, add symbols to global namespace. */
1665 if (env_preload) load_preload(env_preload);
1667 for (struct dso *p=head; p; p=p->next)
1670 /* Attach to vdso, if provided by the kernel, last so that it does
1671 * not become part of the global namespace. */
1672 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1673 Ehdr *ehdr = (void *)vdso_base;
1674 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1675 vdso.phnum = ehdr->e_phnum;
1676 vdso.phentsize = ehdr->e_phentsize;
1677 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1678 if (phdr->p_type == PT_DYNAMIC)
1679 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1680 if (phdr->p_type == PT_LOAD)
1681 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1684 vdso.shortname = "linux-gate.so.1";
1692 for (i=0; app.dynv[i]; i+=2) {
1693 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1694 app.dynv[i+1] = (size_t)&debug;
1695 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1696 size_t *ptr = (size_t *) app.dynv[i+1];
1697 *ptr = (size_t)&debug;
1701 /* The main program must be relocated LAST since it may contin
1702 * copy relocations which depend on libraries' relocations. */
1703 reloc_all(app.next);
1707 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1708 void *initial_tls = calloc(libc.tls_size, 1);
1710 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1711 argv[0], libc.tls_size);
1714 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1718 size_t tmp_tls_size = libc.tls_size;
1719 pthread_t self = __pthread_self();
1720 /* Temporarily set the tls size to the full size of
1721 * builtin_tls so that __copy_tls will use the same layout
1722 * as it did for before. Then check, just to be safe. */
1723 libc.tls_size = sizeof builtin_tls;
1724 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1725 libc.tls_size = tmp_tls_size;
1727 static_tls_cnt = tls_cnt;
1729 if (ldso_fail) _exit(127);
1730 if (ldd_mode) _exit(0);
1732 /* Determine if malloc was interposed by a replacement implementation
1733 * so that calloc and the memalign family can harden against the
1734 * possibility of incomplete replacement. */
1735 if (find_sym(head, "malloc", 1).dso != &ldso)
1736 __malloc_replaced = 1;
1738 /* Switch to runtime mode: any further failures in the dynamic
1739 * linker are a reportable failure rather than a fatal startup
1744 debug.bp = dl_debug_state;
1746 debug.base = ldso.base;
1750 if (replace_argv0) argv[0] = replace_argv0;
1754 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1758 static void prepare_lazy(struct dso *p)
1760 size_t dyn[DYN_CNT], n, flags1=0;
1761 decode_vec(p->dynv, dyn, DYN_CNT);
1762 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1763 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1765 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1766 if (NEED_MIPS_GOT_RELOCS) {
1767 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1768 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1771 p->lazy = calloc(n, 3*sizeof(size_t));
1773 error("Error preparing lazy relocation for %s: %m", p->name);
1774 longjmp(*rtld_fail, 1);
1776 p->lazy_next = lazy_head;
1780 void *dlopen(const char *file, int mode)
1782 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1783 struct tls_module *orig_tls_tail;
1784 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1789 if (!file) return head;
1791 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1792 pthread_rwlock_wrlock(&lock);
1796 orig_tls_tail = tls_tail;
1797 orig_tls_cnt = tls_cnt;
1798 orig_tls_offset = tls_offset;
1799 orig_tls_align = tls_align;
1800 orig_lazy_head = lazy_head;
1801 orig_syms_tail = syms_tail;
1803 noload = mode & RTLD_NOLOAD;
1806 if (setjmp(*rtld_fail)) {
1807 /* Clean up anything new that was (partially) loaded */
1808 revert_syms(orig_syms_tail);
1809 for (p=orig_tail->next; p; p=next) {
1811 while (p->td_index) {
1812 void *tmp = p->td_index->next;
1817 if (p->rpath != p->rpath_orig)
1819 if (p->deps != &nodeps_dummy)
1824 if (!orig_tls_tail) libc.tls_head = 0;
1825 tls_tail = orig_tls_tail;
1826 if (tls_tail) tls_tail->next = 0;
1827 tls_cnt = orig_tls_cnt;
1828 tls_offset = orig_tls_offset;
1829 tls_align = orig_tls_align;
1830 lazy_head = orig_lazy_head;
1835 } else p = load_library(file, head);
1839 "Library %s is not already loaded" :
1840 "Error loading shared library %s: %m",
1845 /* First load handling */
1846 int first_load = !p->deps;
1849 if (!p->relocated && (mode & RTLD_LAZY)) {
1851 for (i=0; p->deps[i]; i++)
1852 if (!p->deps[i]->relocated)
1853 prepare_lazy(p->deps[i]);
1856 if (first_load || (mode & RTLD_GLOBAL)) {
1857 /* Make new symbols global, at least temporarily, so we can do
1858 * relocations. If not RTLD_GLOBAL, this is reverted below. */
1860 for (i=0; p->deps[i]; i++)
1861 add_syms(p->deps[i]);
1867 /* If RTLD_GLOBAL was not specified, undo any new additions
1868 * to the global symbol table. This is a nop if the library was
1869 * previously loaded and already global. */
1870 if (!(mode & RTLD_GLOBAL))
1871 revert_syms(orig_syms_tail);
1873 /* Processing of deferred lazy relocations must not happen until
1874 * the new libraries are committed; otherwise we could end up with
1875 * relocations resolved to symbol definitions that get removed. */
1879 if (tls_cnt != orig_tls_cnt)
1886 pthread_rwlock_unlock(&lock);
1887 if (p) do_init_fini(orig_tail);
1888 pthread_setcancelstate(cs, 0);
1892 hidden int __dl_invalid_handle(void *h)
1895 for (p=head; p; p=p->next) if (h==p) return 0;
1896 error("Invalid library handle %p", (void *)h);
1900 static void *addr2dso(size_t a)
1904 if (DL_FDPIC) for (p=head; p; p=p->next) {
1906 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1909 for (p=head; p; p=p->next) {
1910 if (DL_FDPIC && p->loadmap) {
1911 for (i=0; i<p->loadmap->nsegs; i++) {
1912 if (a-p->loadmap->segs[i].p_vaddr
1913 < p->loadmap->segs[i].p_memsz)
1918 size_t phcnt = p->phnum;
1919 size_t entsz = p->phentsize;
1920 size_t base = (size_t)p->base;
1921 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
1922 if (ph->p_type != PT_LOAD) continue;
1923 if (a-base-ph->p_vaddr < ph->p_memsz)
1926 if (a-(size_t)p->map < p->map_len)
1933 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1936 uint32_t h = 0, gh = 0, *ght;
1938 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1939 if (p == RTLD_DEFAULT) {
1941 } else if (p == RTLD_NEXT) {
1942 p = addr2dso((size_t)ra);
1946 struct symdef def = find_sym(p, s, 0);
1947 if (!def.sym) goto failed;
1948 if ((def.sym->st_info&0xf) == STT_TLS)
1949 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
1950 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
1951 return def.dso->funcdescs + (def.sym - def.dso->syms);
1952 return laddr(def.dso, def.sym->st_value);
1954 if (__dl_invalid_handle(p))
1956 if ((ght = p->ghashtab)) {
1958 sym = gnu_lookup(gh, ght, p, s);
1961 sym = sysv_lookup(s, h, p);
1963 if (sym && (sym->st_info&0xf) == STT_TLS)
1964 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
1965 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1966 return p->funcdescs + (sym - p->syms);
1967 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1968 return laddr(p, sym->st_value);
1969 for (i=0; p->deps[i]; i++) {
1970 if ((ght = p->deps[i]->ghashtab)) {
1971 if (!gh) gh = gnu_hash(s);
1972 sym = gnu_lookup(gh, ght, p->deps[i], s);
1974 if (!h) h = sysv_hash(s);
1975 sym = sysv_lookup(s, h, p->deps[i]);
1977 if (sym && (sym->st_info&0xf) == STT_TLS)
1978 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
1979 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1980 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
1981 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1982 return laddr(p->deps[i], sym->st_value);
1985 error("Symbol not found: %s", s);
1989 int dladdr(const void *addr_arg, Dl_info *info)
1991 size_t addr = (size_t)addr_arg;
1997 size_t besterr = -1;
1999 pthread_rwlock_rdlock(&lock);
2001 pthread_rwlock_unlock(&lock);
2006 strings = p->strings;
2007 nsym = count_syms(p);
2010 size_t idx = (addr-(size_t)p->funcdescs)
2011 / sizeof(*p->funcdescs);
2012 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2013 best = (size_t)(p->funcdescs + idx);
2014 bestsym = sym + idx;
2019 if (!best) for (; nsym; nsym--, sym++) {
2021 && (1<<(sym->st_info&0xf) & OK_TYPES)
2022 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2023 size_t symaddr = (size_t)laddr(p, sym->st_value);
2024 if (symaddr > addr || symaddr <= best)
2028 besterr = addr - symaddr;
2029 if (addr == symaddr)
2034 if (bestsym && besterr > bestsym->st_size-1) {
2039 info->dli_fname = p->name;
2040 info->dli_fbase = p->map;
2043 info->dli_sname = 0;
2044 info->dli_saddr = 0;
2048 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2049 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2050 info->dli_sname = strings + bestsym->st_name;
2051 info->dli_saddr = (void *)best;
2056 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2059 pthread_rwlock_rdlock(&lock);
2060 res = do_dlsym(p, s, ra);
2061 pthread_rwlock_unlock(&lock);
2065 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2067 struct dso *current;
2068 struct dl_phdr_info info;
2070 for(current = head; current;) {
2071 info.dlpi_addr = (uintptr_t)current->base;
2072 info.dlpi_name = current->name;
2073 info.dlpi_phdr = current->phdr;
2074 info.dlpi_phnum = current->phnum;
2075 info.dlpi_adds = gencnt;
2077 info.dlpi_tls_modid = current->tls_id;
2078 info.dlpi_tls_data = current->tls.image;
2080 ret = (callback)(&info, sizeof (info), data);
2082 if (ret != 0) break;
2084 pthread_rwlock_rdlock(&lock);
2085 current = current->next;
2086 pthread_rwlock_unlock(&lock);
2091 static void error(const char *fmt, ...)
2096 vdprintf(2, fmt, ap);
2102 __dl_vseterr(fmt, ap);