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;
76 struct dso **deps, *needed_by;
78 char *rpath_orig, *rpath;
79 struct tls_module tls;
81 size_t relro_start, relro_end;
83 unsigned char *new_tls;
84 volatile int new_dtv_idx, new_tls_idx;
85 struct td_index *td_index;
86 struct dso *fini_next;
91 struct fdpic_loadmap *loadmap;
106 static struct builtin_tls {
111 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
113 #define ADDEND_LIMIT 4096
114 static size_t *saved_addends, *apply_addends_to;
116 static struct dso ldso;
117 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
118 static char *env_path, *sys_path;
119 static unsigned long long gencnt;
122 static int ldso_fail;
124 static jmp_buf *rtld_fail;
125 static pthread_rwlock_t lock;
126 static struct debug debug;
127 static struct tls_module *tls_tail;
128 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
129 static size_t static_tls_cnt;
130 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
131 static struct fdpic_loadmap *app_loadmap;
132 static struct fdpic_dummy_loadmap app_dummy_loadmap;
134 struct debug *_dl_debug_addr = &debug;
136 extern hidden int __malloc_replaced;
138 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
140 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
142 weak_alias(__init_array_start, __init_array_end);
143 weak_alias(__fini_array_start, __fini_array_end);
145 static int dl_strcmp(const char *l, const char *r)
147 for (; *l==*r && *l; l++, r++);
148 return *(unsigned char *)l - *(unsigned char *)r;
150 #define strcmp(l,r) dl_strcmp(l,r)
152 /* Compute load address for a virtual address in a given dso. */
154 static void *laddr(const struct dso *p, size_t v)
157 if (!p->loadmap) return p->base + v;
158 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
159 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
161 static void *laddr_pg(const struct dso *p, size_t v)
164 size_t pgsz = PAGE_SIZE;
165 if (!p->loadmap) return p->base + v;
167 size_t a = p->loadmap->segs[j].p_vaddr;
168 size_t b = a + p->loadmap->segs[j].p_memsz;
174 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
176 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
177 laddr(p, v), (p)->got })
179 #define laddr(p, v) (void *)((p)->base + (v))
180 #define laddr_pg(p, v) laddr(p, v)
181 #define fpaddr(p, v) ((void (*)())laddr(p, v))
184 static void decode_vec(size_t *v, size_t *a, size_t cnt)
187 for (i=0; i<cnt; i++) a[i] = 0;
188 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
194 static int search_vec(size_t *v, size_t *r, size_t key)
196 for (; v[0]!=key; v+=2)
202 static uint32_t sysv_hash(const char *s0)
204 const unsigned char *s = (void *)s0;
210 return h & 0xfffffff;
213 static uint32_t gnu_hash(const char *s0)
215 const unsigned char *s = (void *)s0;
216 uint_fast32_t h = 5381;
222 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
225 Sym *syms = dso->syms;
226 Elf_Symndx *hashtab = dso->hashtab;
227 char *strings = dso->strings;
228 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
229 if ((!dso->versym || dso->versym[i] >= 0)
230 && (!strcmp(s, strings+syms[i].st_name)))
236 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
238 uint32_t nbuckets = hashtab[0];
239 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
240 uint32_t i = buckets[h1 % nbuckets];
244 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
246 for (h1 |= 1; ; i++) {
247 uint32_t h2 = *hashval++;
248 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
249 && !strcmp(s, dso->strings + dso->syms[i].st_name))
257 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
259 const size_t *bloomwords = (const void *)(hashtab+4);
260 size_t f = bloomwords[fofs & (hashtab[2]-1)];
261 if (!(f & fmask)) return 0;
263 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
264 if (!(f & 1)) return 0;
266 return gnu_lookup(h1, hashtab, dso, s);
269 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
270 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
272 #ifndef ARCH_SYM_REJECT_UND
273 #define ARCH_SYM_REJECT_UND(s) 0
276 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
278 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
279 size_t ghm = 1ul << gh % (8*sizeof(size_t));
280 struct symdef def = {0};
281 for (; dso; dso=dso->syms_next) {
283 if ((ght = dso->ghashtab)) {
284 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
286 if (!h) h = sysv_hash(s);
287 sym = sysv_lookup(s, h, dso);
291 if (need_def || (sym->st_info&0xf) == STT_TLS
292 || ARCH_SYM_REJECT_UND(sym))
295 if ((sym->st_info&0xf) != STT_TLS)
297 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
298 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
306 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
308 unsigned char *base = dso->base;
309 Sym *syms = dso->syms;
310 char *strings = dso->strings;
321 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
324 /* Only ldso's REL table needs addend saving/reuse. */
325 if (rel == apply_addends_to)
330 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
331 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
332 type = R_TYPE(rel[1]);
333 if (type == REL_NONE) continue;
334 reloc_addr = laddr(dso, rel[0]);
338 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
340 } else if (reuse_addends) {
341 /* Save original addend in stage 2 where the dso
342 * chain consists of just ldso; otherwise read back
343 * saved addend since the inline one was clobbered. */
345 saved_addends[save_slot] = *reloc_addr;
346 addend = saved_addends[save_slot++];
348 addend = *reloc_addr;
351 sym_index = R_SYM(rel[1]);
353 sym = syms + sym_index;
354 name = strings + sym->st_name;
355 ctx = type==REL_COPY ? head->syms_next : head;
356 def = (sym->st_info&0xf) == STT_SECTION
357 ? (struct symdef){ .dso = dso, .sym = sym }
358 : find_sym(ctx, name, type==REL_PLT);
359 if (!def.sym && (sym->st_shndx != SHN_UNDEF
360 || sym->st_info>>4 != STB_WEAK)) {
361 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
362 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
363 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
364 dso->lazy[3*dso->lazy_cnt+2] = addend;
368 error("Error relocating %s: %s: symbol not found",
370 if (runtime) longjmp(*rtld_fail, 1);
379 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
380 tls_val = def.sym ? def.sym->st_value : 0;
382 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
383 && runtime && def.dso->tls_id > static_tls_cnt) {
384 error("Error relocating %s: %s: initial-exec TLS "
385 "resolves to dynamic definition in %s",
386 dso->name, name, def.dso->name);
387 longjmp(*rtld_fail, 1);
394 addend -= (size_t)reloc_addr;
398 *reloc_addr = sym_val + addend;
401 *reloc_addr = (size_t)base + addend;
404 if (sym) *reloc_addr = sym_val + addend;
405 else *reloc_addr = (size_t)base + addend;
408 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
411 *(uint32_t *)reloc_addr = sym_val + addend
412 - (size_t)reloc_addr;
415 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
416 + (def.sym - def.dso->syms)) : 0;
418 case REL_FUNCDESC_VAL:
419 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
420 else *reloc_addr = sym_val;
421 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
424 *reloc_addr = def.dso->tls_id;
427 *reloc_addr = tls_val + addend - DTP_OFFSET;
431 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
435 *reloc_addr = tls_val - def.dso->tls.offset + addend;
438 *reloc_addr = def.dso->tls.offset - tls_val + addend;
442 if (stride<3) addend = reloc_addr[1];
443 if (runtime && def.dso->tls_id > static_tls_cnt) {
444 struct td_index *new = malloc(sizeof *new);
447 "Error relocating %s: cannot allocate TLSDESC for %s",
448 dso->name, sym ? name : "(local)" );
449 longjmp(*rtld_fail, 1);
451 new->next = dso->td_index;
453 new->args[0] = def.dso->tls_id;
454 new->args[1] = tls_val + addend - DTP_OFFSET;
455 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
456 reloc_addr[1] = (size_t)new;
458 reloc_addr[0] = (size_t)__tlsdesc_static;
460 reloc_addr[1] = tls_val + def.dso->tls.offset
463 reloc_addr[1] = tls_val - def.dso->tls.offset
467 #ifdef TLSDESC_BACKWARDS
468 /* Some archs (32-bit ARM at least) invert the order of
469 * the descriptor members. Fix them up here. */
470 size_t tmp = reloc_addr[0];
471 reloc_addr[0] = reloc_addr[1];
476 error("Error relocating %s: unsupported relocation type %d",
478 if (runtime) longjmp(*rtld_fail, 1);
484 static void redo_lazy_relocs()
486 struct dso *p = lazy_head, *next;
490 size_t size = p->lazy_cnt*3*sizeof(size_t);
492 do_relocs(p, p->lazy, size, 3);
494 p->lazy_next = lazy_head;
504 /* A huge hack: to make up for the wastefulness of shared libraries
505 * needing at least a page of dirty memory even if they have no global
506 * data, we reclaim the gaps at the beginning and end of writable maps
507 * and "donate" them to the heap. */
509 static void reclaim(struct dso *dso, size_t start, size_t end)
511 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
512 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
513 if (start >= end) return;
514 char *base = laddr_pg(dso, start);
515 __malloc_donate(base, base+(end-start));
518 static void reclaim_gaps(struct dso *dso)
520 Phdr *ph = dso->phdr;
521 size_t phcnt = dso->phnum;
523 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
524 if (ph->p_type!=PT_LOAD) continue;
525 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
526 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
527 reclaim(dso, ph->p_vaddr+ph->p_memsz,
528 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
532 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
534 static int no_map_fixed;
537 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
538 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
542 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
543 if (flags & MAP_ANONYMOUS) {
548 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
549 for (q=p; n; q+=r, off+=r, n-=r) {
551 if (r < 0 && errno != EINTR) return MAP_FAILED;
560 static void unmap_library(struct dso *dso)
564 for (i=0; i<dso->loadmap->nsegs; i++) {
565 if (!dso->loadmap->segs[i].p_memsz)
567 munmap((void *)dso->loadmap->segs[i].addr,
568 dso->loadmap->segs[i].p_memsz);
571 } else if (dso->map && dso->map_len) {
572 munmap(dso->map, dso->map_len);
576 static void *map_library(int fd, struct dso *dso)
578 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
579 void *allocated_buf=0;
581 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
582 size_t this_min, this_max;
588 unsigned char *map=MAP_FAILED, *base;
593 ssize_t l = read(fd, buf, sizeof buf);
596 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
598 phsize = eh->e_phentsize * eh->e_phnum;
599 if (phsize > sizeof buf - sizeof *eh) {
600 allocated_buf = malloc(phsize);
601 if (!allocated_buf) return 0;
602 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
603 if (l < 0) goto error;
604 if (l != phsize) goto noexec;
605 ph = ph0 = allocated_buf;
606 } else if (eh->e_phoff + phsize > l) {
607 l = pread(fd, buf+1, phsize, eh->e_phoff);
608 if (l < 0) goto error;
609 if (l != phsize) goto noexec;
610 ph = ph0 = (void *)(buf + 1);
612 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
614 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
615 if (ph->p_type == PT_DYNAMIC) {
617 } else if (ph->p_type == PT_TLS) {
618 tls_image = ph->p_vaddr;
619 dso->tls.align = ph->p_align;
620 dso->tls.len = ph->p_filesz;
621 dso->tls.size = ph->p_memsz;
622 } else if (ph->p_type == PT_GNU_RELRO) {
623 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
624 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
625 } else if (ph->p_type == PT_GNU_STACK) {
626 if (!runtime && ph->p_memsz > __default_stacksize) {
627 __default_stacksize =
628 ph->p_memsz < DEFAULT_STACK_MAX ?
629 ph->p_memsz : DEFAULT_STACK_MAX;
632 if (ph->p_type != PT_LOAD) continue;
634 if (ph->p_vaddr < addr_min) {
635 addr_min = ph->p_vaddr;
636 off_start = ph->p_offset;
637 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
638 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
639 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
641 if (ph->p_vaddr+ph->p_memsz > addr_max) {
642 addr_max = ph->p_vaddr+ph->p_memsz;
645 if (!dyn) goto noexec;
646 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
647 dso->loadmap = calloc(1, sizeof *dso->loadmap
648 + nsegs * sizeof *dso->loadmap->segs);
649 if (!dso->loadmap) goto error;
650 dso->loadmap->nsegs = nsegs;
651 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
652 if (ph->p_type != PT_LOAD) continue;
653 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
654 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
655 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
656 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
658 fd, ph->p_offset & -PAGE_SIZE);
659 if (map == MAP_FAILED) {
663 dso->loadmap->segs[i].addr = (size_t)map +
664 (ph->p_vaddr & PAGE_SIZE-1);
665 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
666 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
668 if (prot & PROT_WRITE) {
669 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
671 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
672 size_t pgend = brk + ph->p_memsz - ph->p_filesz
673 + PAGE_SIZE-1 & -PAGE_SIZE;
674 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
676 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
677 -1, off_start) == MAP_FAILED)
679 memset(map + brk, 0, pgbrk-brk);
682 map = (void *)dso->loadmap->segs[0].addr;
686 addr_max += PAGE_SIZE-1;
687 addr_max &= -PAGE_SIZE;
688 addr_min &= -PAGE_SIZE;
689 off_start &= -PAGE_SIZE;
690 map_len = addr_max - addr_min + off_start;
691 /* The first time, we map too much, possibly even more than
692 * the length of the file. This is okay because we will not
693 * use the invalid part; we just need to reserve the right
694 * amount of virtual address space to map over later. */
695 map = DL_NOMMU_SUPPORT
696 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
697 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
698 : mmap((void *)addr_min, map_len, prot,
699 MAP_PRIVATE, fd, off_start);
700 if (map==MAP_FAILED) goto error;
702 dso->map_len = map_len;
703 /* If the loaded file is not relocatable and the requested address is
704 * not available, then the load operation must fail. */
705 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
709 base = map - addr_min;
712 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
713 if (ph->p_type != PT_LOAD) continue;
714 /* Check if the programs headers are in this load segment, and
715 * if so, record the address for use by dl_iterate_phdr. */
716 if (!dso->phdr && eh->e_phoff >= ph->p_offset
717 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
718 dso->phdr = (void *)(base + ph->p_vaddr
719 + (eh->e_phoff-ph->p_offset));
720 dso->phnum = eh->e_phnum;
721 dso->phentsize = eh->e_phentsize;
723 this_min = ph->p_vaddr & -PAGE_SIZE;
724 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
725 off_start = ph->p_offset & -PAGE_SIZE;
726 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
727 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
728 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
729 /* Reuse the existing mapping for the lowest-address LOAD */
730 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
731 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
733 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
734 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
735 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
736 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
737 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)
741 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
742 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
743 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
750 dso->dynv = laddr(dso, dyn);
751 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
757 if (map!=MAP_FAILED) unmap_library(dso);
762 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
767 s += strspn(s, ":\n");
768 l = strcspn(s, ":\n");
769 if (l-1 >= INT_MAX) return -1;
770 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
771 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
779 /* Any negative value but -1 will inhibit
780 * futher path search. */
788 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
791 const char *s, *t, *origin;
793 if (p->rpath || !p->rpath_orig) return 0;
794 if (!strchr(p->rpath_orig, '$')) {
795 p->rpath = p->rpath_orig;
800 while ((t=strchr(s, '$'))) {
801 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
806 if (n > SSIZE_MAX/PATH_MAX) return 0;
808 if (p->kernel_mapped) {
809 /* $ORIGIN searches cannot be performed for the main program
810 * when it is suid/sgid/AT_SECURE. This is because the
811 * pathname is under the control of the caller of execve.
812 * For libraries, however, $ORIGIN can be processed safely
813 * since the library's pathname came from a trusted source
814 * (either system paths or a call to dlopen). */
817 l = readlink("/proc/self/exe", buf, buf_size);
818 if (l == -1) switch (errno) {
833 t = strrchr(origin, '/');
837 /* Normally p->name will always be an absolute or relative
838 * pathname containing at least one '/' character, but in the
839 * case where ldso was invoked as a command to execute a
840 * program in the working directory, app.name may not. Fix. */
844 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
845 if (libc.secure && *origin != '/')
847 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
848 if (!p->rpath) return -1;
852 while ((t=strchr(s, '$'))) {
855 memcpy(d, origin, l);
857 /* It was determined previously that the '$' is followed
858 * either by "ORIGIN" or "{ORIGIN}". */
859 s = t + 7 + 2*(t[1]=='{');
865 static void decode_dyn(struct dso *p)
868 decode_vec(p->dynv, dyn, DYN_CNT);
869 p->syms = laddr(p, dyn[DT_SYMTAB]);
870 p->strings = laddr(p, dyn[DT_STRTAB]);
871 if (dyn[0]&(1<<DT_HASH))
872 p->hashtab = laddr(p, dyn[DT_HASH]);
873 if (dyn[0]&(1<<DT_RPATH))
874 p->rpath_orig = p->strings + dyn[DT_RPATH];
875 if (dyn[0]&(1<<DT_RUNPATH))
876 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
877 if (dyn[0]&(1<<DT_PLTGOT))
878 p->got = laddr(p, dyn[DT_PLTGOT]);
879 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
880 p->ghashtab = laddr(p, *dyn);
881 if (search_vec(p->dynv, dyn, DT_VERSYM))
882 p->versym = laddr(p, *dyn);
885 static size_t count_syms(struct dso *p)
887 if (p->hashtab) return p->hashtab[1];
890 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
892 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
893 if (buckets[i] > nsym)
897 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
899 while (!(*hashval++ & 1));
904 static void *dl_mmap(size_t n)
907 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
909 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
911 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
913 return p == MAP_FAILED ? 0 : p;
916 static void makefuncdescs(struct dso *p)
918 static int self_done;
919 size_t nsym = count_syms(p);
920 size_t i, size = nsym * sizeof(*p->funcdescs);
923 p->funcdescs = dl_mmap(size);
926 p->funcdescs = malloc(size);
929 if (!runtime) a_crash();
930 error("Error allocating function descriptors for %s", p->name);
931 longjmp(*rtld_fail, 1);
933 for (i=0; i<nsym; i++) {
934 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
935 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
936 p->funcdescs[i].got = p->got;
938 p->funcdescs[i].addr = 0;
939 p->funcdescs[i].got = 0;
944 static struct dso *load_library(const char *name, struct dso *needed_by)
946 char buf[2*NAME_MAX+2];
947 const char *pathname;
949 struct dso *p, temp_dso = {0};
961 /* Catch and block attempts to reload the implementation itself */
962 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
963 static const char reserved[] =
964 "c.pthread.rt.m.dl.util.xnet.";
965 const char *rp, *next;
966 for (rp=reserved; *rp; rp=next) {
967 next = strchr(rp, '.') + 1;
968 if (strncmp(name+3, rp, next-rp) == 0)
973 /* Track which names have been resolved
974 * and only report each one once. */
975 static unsigned reported;
976 unsigned mask = 1U<<(rp-reserved);
977 if (!(reported & mask)) {
979 dprintf(1, "\t%s => %s (%p)\n",
987 if (!strcmp(name, ldso.name)) is_self = 1;
996 if (strchr(name, '/')) {
998 fd = open(name, O_RDONLY|O_CLOEXEC);
1000 /* Search for the name to see if it's already loaded */
1001 for (p=head->next; p; p=p->next) {
1002 if (p->shortname && !strcmp(p->shortname, name)) {
1006 if (strlen(name) > NAME_MAX) return 0;
1008 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1009 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1010 if (fixup_rpath(p, buf, sizeof buf) < 0)
1011 fd = -2; /* Inhibit further search. */
1013 fd = path_open(name, p->rpath, buf, sizeof buf);
1019 if (ldso.name[0]=='/') {
1021 for (s=t=z=ldso.name; *s; s++)
1022 if (*s=='/') z=t, t=s;
1023 prefix_len = z-ldso.name;
1024 if (prefix_len < PATH_MAX)
1031 char etc_ldso_path[prefix_len + 1
1032 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1033 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1034 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1035 (int)prefix_len, prefix);
1036 FILE *f = fopen(etc_ldso_path, "rbe");
1038 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1043 } else if (errno != ENOENT) {
1047 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1048 fd = path_open(name, sys_path, buf, sizeof buf);
1052 if (fd < 0) return 0;
1053 if (fstat(fd, &st) < 0) {
1057 for (p=head->next; p; p=p->next) {
1058 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1059 /* If this library was previously loaded with a
1060 * pathname but a search found the same inode,
1061 * setup its shortname so it can be found by name. */
1062 if (!p->shortname && pathname != name)
1063 p->shortname = strrchr(p->name, '/')+1;
1068 map = noload ? 0 : map_library(fd, &temp_dso);
1072 /* Avoid the danger of getting two versions of libc mapped into the
1073 * same process when an absolute pathname was used. The symbols
1074 * checked are chosen to catch both musl and glibc, and to avoid
1075 * false positives from interposition-hack libraries. */
1076 decode_dyn(&temp_dso);
1077 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1078 find_sym(&temp_dso, "stdin", 1).sym) {
1079 unmap_library(&temp_dso);
1080 return load_library("libc.so", needed_by);
1082 /* Past this point, if we haven't reached runtime yet, ldso has
1083 * committed either to use the mapped library or to abort execution.
1084 * Unmapping is not possible, so we can safely reclaim gaps. */
1085 if (!runtime) reclaim_gaps(&temp_dso);
1087 /* Allocate storage for the new DSO. When there is TLS, this
1088 * storage must include a reservation for all pre-existing
1089 * threads to obtain copies of both the new TLS, and an
1090 * extended DTV capable of storing an additional slot for
1091 * the newly-loaded DSO. */
1092 alloc_size = sizeof *p + strlen(pathname) + 1;
1093 if (runtime && temp_dso.tls.image) {
1094 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1095 + sizeof(void *) * (tls_cnt+3);
1096 n_th = libc.threads_minus_1 + 1;
1097 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1098 else alloc_size += n_th * per_th;
1100 p = calloc(1, alloc_size);
1102 unmap_library(&temp_dso);
1105 memcpy(p, &temp_dso, sizeof temp_dso);
1108 p->needed_by = needed_by;
1110 strcpy(p->name, pathname);
1111 /* Add a shortname only if name arg was not an explicit pathname. */
1112 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1114 p->tls_id = ++tls_cnt;
1115 tls_align = MAXP2(tls_align, p->tls.align);
1117 p->tls.offset = tls_offset + ( (tls_align-1) &
1118 -(tls_offset + (uintptr_t)p->tls.image) );
1119 tls_offset += p->tls.size;
1121 tls_offset += p->tls.size + p->tls.align - 1;
1122 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1124 p->tls.offset = tls_offset;
1126 p->new_dtv = (void *)(-sizeof(size_t) &
1127 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1128 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1129 if (tls_tail) tls_tail->next = &p->tls;
1130 else libc.tls_head = &p->tls;
1138 if (DL_FDPIC) makefuncdescs(p);
1140 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1145 static void load_direct_deps(struct dso *p)
1148 if (p->deps) return;
1149 for (i=cnt=0; p->dynv[i]; i+=2)
1150 if (p->dynv[i] == DT_NEEDED) cnt++;
1151 p->deps = calloc(cnt+1, sizeof *p->deps);
1153 error("Error loading dependencies for %s", p->name);
1154 if (runtime) longjmp(*rtld_fail, 1);
1156 for (i=cnt=0; p->dynv[i]; i+=2) {
1157 if (p->dynv[i] != DT_NEEDED) continue;
1158 struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
1160 error("Error loading shared library %s: %m (needed by %s)",
1161 p->strings + p->dynv[i+1], p->name);
1162 if (runtime) longjmp(*rtld_fail, 1);
1165 p->deps[cnt++] = dep;
1168 p->ndeps_direct = cnt;
1171 static void load_deps(struct dso *p)
1173 if (p->deps) return;
1174 for (; p; p=p->next)
1175 load_direct_deps(p);
1178 static void extend_bfs_deps(struct dso *p)
1180 size_t i, j, cnt, ndeps_all;
1183 if (p->bfs_built) return;
1184 ndeps_all = p->ndeps_direct;
1186 /* Mark existing (direct) deps so they won't be duplicated. */
1187 for (i=0; p->deps[i]; i++)
1188 p->deps[i]->mark = 1;
1190 /* For each dependency already in the list, copy its list of direct
1191 * dependencies to the list, excluding any items already in the
1192 * list. Note that the list this loop iterates over will grow during
1193 * the loop, but since duplicates are excluded, growth is bounded. */
1194 for (i=0; p->deps[i]; i++) {
1195 struct dso *dep = p->deps[i];
1196 for (j=cnt=0; j<dep->ndeps_direct; j++)
1197 if (!dep->deps[j]->mark) cnt++;
1198 tmp = realloc(p->deps, sizeof(*p->deps) * (ndeps_all+cnt+1));
1200 error("Error recording dependencies for %s", p->name);
1201 if (runtime) longjmp(*rtld_fail, 1);
1205 for (j=0; j<dep->ndeps_direct; j++) {
1206 if (dep->deps[j]->mark) continue;
1207 dep->deps[j]->mark = 1;
1208 p->deps[ndeps_all++] = dep->deps[j];
1210 p->deps[ndeps_all] = 0;
1213 for (p=head; p; p=p->next)
1217 static void load_preload(char *s)
1221 for (z=s; *z; s=z) {
1222 for ( ; *s && (isspace(*s) || *s==':'); s++);
1223 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1231 static void add_syms(struct dso *p)
1233 if (!p->syms_next && syms_tail != p) {
1234 syms_tail->syms_next = p;
1239 static void revert_syms(struct dso *old_tail)
1241 struct dso *p, *next;
1242 /* Chop off the tail of the list of dsos that participate in
1243 * the global symbol table, reverting them to RTLD_LOCAL. */
1244 for (p=old_tail; p; p=next) {
1245 next = p->syms_next;
1248 syms_tail = old_tail;
1251 static void do_mips_relocs(struct dso *p, size_t *got)
1253 size_t i, j, rel[2];
1254 unsigned char *base = p->base;
1255 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1259 while (i--) *got++ += (size_t)base;
1261 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1262 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1263 Sym *sym = p->syms + j;
1264 rel[0] = (unsigned char *)got - base;
1265 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1266 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1267 do_relocs(p, rel, sizeof rel, 2);
1271 static void reloc_all(struct dso *p)
1273 size_t dyn[DYN_CNT];
1274 for (; p; p=p->next) {
1275 if (p->relocated) continue;
1276 decode_vec(p->dynv, dyn, DYN_CNT);
1277 if (NEED_MIPS_GOT_RELOCS)
1278 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1279 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1280 2+(dyn[DT_PLTREL]==DT_RELA));
1281 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1282 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1284 if (head != &ldso && p->relro_start != p->relro_end &&
1285 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1286 && errno != ENOSYS) {
1287 error("Error relocating %s: RELRO protection failed: %m",
1289 if (runtime) longjmp(*rtld_fail, 1);
1296 static void kernel_mapped_dso(struct dso *p)
1298 size_t min_addr = -1, max_addr = 0, cnt;
1300 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1301 if (ph->p_type == PT_DYNAMIC) {
1302 p->dynv = laddr(p, ph->p_vaddr);
1303 } else if (ph->p_type == PT_GNU_RELRO) {
1304 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1305 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1306 } else if (ph->p_type == PT_GNU_STACK) {
1307 if (!runtime && ph->p_memsz > __default_stacksize) {
1308 __default_stacksize =
1309 ph->p_memsz < DEFAULT_STACK_MAX ?
1310 ph->p_memsz : DEFAULT_STACK_MAX;
1313 if (ph->p_type != PT_LOAD) continue;
1314 if (ph->p_vaddr < min_addr)
1315 min_addr = ph->p_vaddr;
1316 if (ph->p_vaddr+ph->p_memsz > max_addr)
1317 max_addr = ph->p_vaddr+ph->p_memsz;
1319 min_addr &= -PAGE_SIZE;
1320 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1321 p->map = p->base + min_addr;
1322 p->map_len = max_addr - min_addr;
1323 p->kernel_mapped = 1;
1326 void __libc_exit_fini()
1329 size_t dyn[DYN_CNT];
1330 for (p=fini_head; p; p=p->fini_next) {
1331 if (!p->constructed) continue;
1332 decode_vec(p->dynv, dyn, DYN_CNT);
1333 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1334 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1335 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1336 while (n--) ((void (*)(void))*--fn)();
1338 #ifndef NO_LEGACY_INITFINI
1339 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1340 fpaddr(p, dyn[DT_FINI])();
1345 static void do_init_fini(struct dso *p)
1347 size_t dyn[DYN_CNT];
1348 int need_locking = libc.threads_minus_1;
1349 /* Allow recursive calls that arise when a library calls
1350 * dlopen from one of its constructors, but block any
1351 * other threads until all ctors have finished. */
1352 if (need_locking) pthread_mutex_lock(&init_fini_lock);
1353 for (; p; p=p->prev) {
1354 if (p->constructed) continue;
1356 decode_vec(p->dynv, dyn, DYN_CNT);
1357 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1358 p->fini_next = fini_head;
1361 #ifndef NO_LEGACY_INITFINI
1362 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1363 fpaddr(p, dyn[DT_INIT])();
1365 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1366 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1367 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1368 while (n--) ((void (*)(void))*fn++)();
1370 if (!need_locking && libc.threads_minus_1) {
1372 pthread_mutex_lock(&init_fini_lock);
1375 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1378 void __libc_start_init(void)
1383 static void dl_debug_state(void)
1387 weak_alias(dl_debug_state, _dl_debug_state);
1389 void __init_tls(size_t *auxv)
1393 static void update_tls_size()
1395 libc.tls_cnt = tls_cnt;
1396 libc.tls_align = tls_align;
1397 libc.tls_size = ALIGN(
1398 (1+tls_cnt) * sizeof(void *) +
1400 sizeof(struct pthread) +
1405 static void install_new_tls(void)
1408 pthread_t self = __pthread_self(), td;
1409 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1410 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1413 size_t old_cnt = self->dtv[0];
1415 __block_app_sigs(&set);
1417 /* Copy existing dtv contents from all existing threads. */
1418 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1419 memcpy(newdtv+i, td->dtv,
1420 (old_cnt+1)*sizeof(uintptr_t));
1421 newdtv[i][0] = tls_cnt;
1423 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1424 for (p=head; ; p=p->next) {
1425 if (p->tls_id <= old_cnt) continue;
1426 unsigned char *mem = p->new_tls;
1427 for (j=0; j<i; j++) {
1428 unsigned char *new = mem;
1429 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1431 memcpy(new, p->tls.image, p->tls.len);
1432 newdtv[j][p->tls_id] =
1433 (uintptr_t)new + DTP_OFFSET;
1434 mem += p->tls.size + p->tls.align;
1436 if (p->tls_id == tls_cnt) break;
1439 /* Broadcast barrier to ensure contents of new dtv is visible
1440 * if the new dtv pointer is. The __membarrier function has a
1441 * fallback emulation using signals for kernels that lack the
1442 * feature at the syscall level. */
1444 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1446 /* Install new dtv for each thread. */
1447 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1448 td->dtv = td->dtv_copy = newdtv[j];
1452 __restore_sigs(&set);
1455 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1456 * following stage 2 and stage 3 functions via primitive symbolic lookup
1457 * since it does not have access to their addresses to begin with. */
1459 /* Stage 2 of the dynamic linker is called after relative relocations
1460 * have been processed. It can make function calls to static functions
1461 * and access string literals and static data, but cannot use extern
1462 * symbols. Its job is to perform symbolic relocations on the dynamic
1463 * linker itself, but some of the relocations performed may need to be
1464 * replaced later due to copy relocations in the main program. */
1466 hidden void __dls2(unsigned char *base, size_t *sp)
1469 void *p1 = (void *)sp[-2];
1470 void *p2 = (void *)sp[-1];
1472 size_t *auxv, aux[AUX_CNT];
1473 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1475 decode_vec(auxv, aux, AUX_CNT);
1476 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1477 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1479 app_loadmap = p2 ? p1 : 0;
1480 ldso.loadmap = p2 ? p2 : p1;
1481 ldso.base = laddr(&ldso, 0);
1485 Ehdr *ehdr = (void *)ldso.base;
1486 ldso.name = ldso.shortname = "libc.so";
1487 ldso.phnum = ehdr->e_phnum;
1488 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1489 ldso.phentsize = ehdr->e_phentsize;
1490 kernel_mapped_dso(&ldso);
1493 if (DL_FDPIC) makefuncdescs(&ldso);
1495 /* Prepare storage for to save clobbered REL addends so they
1496 * can be reused in stage 3. There should be very few. If
1497 * something goes wrong and there are a huge number, abort
1498 * instead of risking stack overflow. */
1499 size_t dyn[DYN_CNT];
1500 decode_vec(ldso.dynv, dyn, DYN_CNT);
1501 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1502 size_t rel_size = dyn[DT_RELSZ];
1503 size_t symbolic_rel_cnt = 0;
1504 apply_addends_to = rel;
1505 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1506 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1507 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1508 size_t addends[symbolic_rel_cnt+1];
1509 saved_addends = addends;
1516 /* Call dynamic linker stage-2b, __dls2b, looking it up
1517 * symbolically as a barrier against moving the address
1518 * load across the above relocation processing. */
1519 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1520 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
1521 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
1524 /* Stage 2b sets up a valid thread pointer, which requires relocations
1525 * completed in stage 2, and on which stage 3 is permitted to depend.
1526 * This is done as a separate stage, with symbolic lookup as a barrier,
1527 * so that loads of the thread pointer and &errno can be pure/const and
1528 * thereby hoistable. */
1530 _Noreturn void __dls2b(size_t *sp)
1532 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1533 * use during dynamic linking. If possible it will also serve as the
1534 * thread pointer at runtime. */
1535 libc.tls_size = sizeof builtin_tls;
1536 libc.tls_align = tls_align;
1537 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1541 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1542 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1543 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1546 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1547 * fully functional. Its job is to load (if not already loaded) and
1548 * process dependencies and relocations for the main application and
1549 * transfer control to its entry point. */
1551 _Noreturn void __dls3(size_t *sp)
1553 static struct dso app, vdso;
1554 size_t aux[AUX_CNT], *auxv;
1556 char *env_preload=0;
1557 char *replace_argv0=0;
1560 char **argv = (void *)(sp+1);
1561 char **argv_orig = argv;
1562 char **envp = argv+argc+1;
1564 /* Find aux vector just past environ[] and use it to initialize
1565 * global data that may be needed before we can make syscalls. */
1567 for (i=argc+1; argv[i]; i++);
1568 libc.auxv = auxv = (void *)(argv+i+1);
1569 decode_vec(auxv, aux, AUX_CNT);
1570 __hwcap = aux[AT_HWCAP];
1571 libc.page_size = aux[AT_PAGESZ];
1572 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1573 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1575 /* Only trust user/env if kernel says we're not suid/sgid */
1577 env_path = getenv("LD_LIBRARY_PATH");
1578 env_preload = getenv("LD_PRELOAD");
1581 /* If the main program was already loaded by the kernel,
1582 * AT_PHDR will point to some location other than the dynamic
1583 * linker's program headers. */
1584 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1585 size_t interp_off = 0;
1586 size_t tls_image = 0;
1587 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1588 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1589 app.phnum = aux[AT_PHNUM];
1590 app.phentsize = aux[AT_PHENT];
1591 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1592 if (phdr->p_type == PT_PHDR)
1593 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1594 else if (phdr->p_type == PT_INTERP)
1595 interp_off = (size_t)phdr->p_vaddr;
1596 else if (phdr->p_type == PT_TLS) {
1597 tls_image = phdr->p_vaddr;
1598 app.tls.len = phdr->p_filesz;
1599 app.tls.size = phdr->p_memsz;
1600 app.tls.align = phdr->p_align;
1603 if (DL_FDPIC) app.loadmap = app_loadmap;
1604 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1605 if (interp_off) ldso.name = laddr(&app, interp_off);
1606 if ((aux[0] & (1UL<<AT_EXECFN))
1607 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1608 app.name = (char *)aux[AT_EXECFN];
1611 kernel_mapped_dso(&app);
1614 char *ldname = argv[0];
1615 size_t l = strlen(ldname);
1616 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1618 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1619 char *opt = argv[0]+2;
1620 *argv++ = (void *)-1;
1623 } else if (!memcmp(opt, "list", 5)) {
1625 } else if (!memcmp(opt, "library-path", 12)) {
1626 if (opt[12]=='=') env_path = opt+13;
1627 else if (opt[12]) *argv = 0;
1628 else if (*argv) env_path = *argv++;
1629 } else if (!memcmp(opt, "preload", 7)) {
1630 if (opt[7]=='=') env_preload = opt+8;
1631 else if (opt[7]) *argv = 0;
1632 else if (*argv) env_preload = *argv++;
1633 } else if (!memcmp(opt, "argv0", 5)) {
1634 if (opt[5]=='=') replace_argv0 = opt+6;
1635 else if (opt[5]) *argv = 0;
1636 else if (*argv) replace_argv0 = *argv++;
1641 argv[-1] = (void *)(argc - (argv-argv_orig));
1643 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1645 "Dynamic Program Loader\n"
1646 "Usage: %s [options] [--] pathname%s\n",
1647 __libc_version, ldname,
1648 ldd_mode ? "" : " [args]");
1651 fd = open(argv[0], O_RDONLY);
1653 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1656 Ehdr *ehdr = (void *)map_library(fd, &app);
1658 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1664 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1665 /* Find the name that would have been used for the dynamic
1666 * linker had ldd not taken its place. */
1668 for (i=0; i<app.phnum; i++) {
1669 if (app.phdr[i].p_type == PT_INTERP)
1670 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1672 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1676 libc.tls_head = tls_tail = &app.tls;
1677 app.tls_id = tls_cnt = 1;
1679 app.tls.offset = GAP_ABOVE_TP;
1680 app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
1681 tls_offset = app.tls.offset + app.tls.size
1682 + ( -((uintptr_t)app.tls.image + app.tls.size)
1683 & (app.tls.align-1) );
1685 tls_offset = app.tls.offset = app.tls.size
1686 + ( -((uintptr_t)app.tls.image + app.tls.size)
1687 & (app.tls.align-1) );
1689 tls_align = MAXP2(tls_align, app.tls.align);
1693 makefuncdescs(&app);
1695 app.loadmap = (void *)&app_dummy_loadmap;
1696 app.loadmap->nsegs = 1;
1697 app.loadmap->segs[0].addr = (size_t)app.map;
1698 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1700 app.loadmap->segs[0].p_memsz = app.map_len;
1702 argv[-3] = (void *)app.loadmap;
1705 /* Initial dso chain consists only of the app. */
1706 head = tail = syms_tail = &app;
1708 /* Donate unused parts of app and library mapping to malloc */
1710 reclaim_gaps(&ldso);
1712 /* Load preload/needed libraries, add symbols to global namespace. */
1713 if (env_preload) load_preload(env_preload);
1715 for (struct dso *p=head; p; p=p->next)
1718 /* Attach to vdso, if provided by the kernel, last so that it does
1719 * not become part of the global namespace. */
1720 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1721 Ehdr *ehdr = (void *)vdso_base;
1722 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1723 vdso.phnum = ehdr->e_phnum;
1724 vdso.phentsize = ehdr->e_phentsize;
1725 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1726 if (phdr->p_type == PT_DYNAMIC)
1727 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1728 if (phdr->p_type == PT_LOAD)
1729 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1732 vdso.shortname = "linux-gate.so.1";
1740 for (i=0; app.dynv[i]; i+=2) {
1741 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1742 app.dynv[i+1] = (size_t)&debug;
1743 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1744 size_t *ptr = (size_t *) app.dynv[i+1];
1745 *ptr = (size_t)&debug;
1749 /* The main program must be relocated LAST since it may contin
1750 * copy relocations which depend on libraries' relocations. */
1751 reloc_all(app.next);
1755 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1756 void *initial_tls = calloc(libc.tls_size, 1);
1758 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1759 argv[0], libc.tls_size);
1762 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1766 size_t tmp_tls_size = libc.tls_size;
1767 pthread_t self = __pthread_self();
1768 /* Temporarily set the tls size to the full size of
1769 * builtin_tls so that __copy_tls will use the same layout
1770 * as it did for before. Then check, just to be safe. */
1771 libc.tls_size = sizeof builtin_tls;
1772 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1773 libc.tls_size = tmp_tls_size;
1775 static_tls_cnt = tls_cnt;
1777 if (ldso_fail) _exit(127);
1778 if (ldd_mode) _exit(0);
1780 /* Determine if malloc was interposed by a replacement implementation
1781 * so that calloc and the memalign family can harden against the
1782 * possibility of incomplete replacement. */
1783 if (find_sym(head, "malloc", 1).dso != &ldso)
1784 __malloc_replaced = 1;
1786 /* Switch to runtime mode: any further failures in the dynamic
1787 * linker are a reportable failure rather than a fatal startup
1792 debug.bp = dl_debug_state;
1794 debug.base = ldso.base;
1798 if (replace_argv0) argv[0] = replace_argv0;
1802 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1806 static void prepare_lazy(struct dso *p)
1808 size_t dyn[DYN_CNT], n, flags1=0;
1809 decode_vec(p->dynv, dyn, DYN_CNT);
1810 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1811 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1813 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1814 if (NEED_MIPS_GOT_RELOCS) {
1815 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1816 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1819 p->lazy = calloc(n, 3*sizeof(size_t));
1821 error("Error preparing lazy relocation for %s: %m", p->name);
1822 longjmp(*rtld_fail, 1);
1824 p->lazy_next = lazy_head;
1828 void *dlopen(const char *file, int mode)
1830 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1831 struct tls_module *orig_tls_tail;
1832 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1837 if (!file) return head;
1839 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1840 pthread_rwlock_wrlock(&lock);
1844 orig_tls_tail = tls_tail;
1845 orig_tls_cnt = tls_cnt;
1846 orig_tls_offset = tls_offset;
1847 orig_tls_align = tls_align;
1848 orig_lazy_head = lazy_head;
1849 orig_syms_tail = syms_tail;
1851 noload = mode & RTLD_NOLOAD;
1854 if (setjmp(*rtld_fail)) {
1855 /* Clean up anything new that was (partially) loaded */
1856 revert_syms(orig_syms_tail);
1857 for (p=orig_tail->next; p; p=next) {
1859 while (p->td_index) {
1860 void *tmp = p->td_index->next;
1865 if (p->rpath != p->rpath_orig)
1871 if (!orig_tls_tail) libc.tls_head = 0;
1872 tls_tail = orig_tls_tail;
1873 if (tls_tail) tls_tail->next = 0;
1874 tls_cnt = orig_tls_cnt;
1875 tls_offset = orig_tls_offset;
1876 tls_align = orig_tls_align;
1877 lazy_head = orig_lazy_head;
1882 } else p = load_library(file, head);
1886 "Library %s is not already loaded" :
1887 "Error loading shared library %s: %m",
1892 /* First load handling */
1895 if (!p->relocated && (mode & RTLD_LAZY)) {
1897 for (i=0; p->deps[i]; i++)
1898 if (!p->deps[i]->relocated)
1899 prepare_lazy(p->deps[i]);
1901 if (!p->relocated || (mode & RTLD_GLOBAL)) {
1902 /* Make new symbols global, at least temporarily, so we can do
1903 * relocations. If not RTLD_GLOBAL, this is reverted below. */
1905 for (i=0; p->deps[i]; i++)
1906 add_syms(p->deps[i]);
1908 if (!p->relocated) {
1912 /* If RTLD_GLOBAL was not specified, undo any new additions
1913 * to the global symbol table. This is a nop if the library was
1914 * previously loaded and already global. */
1915 if (!(mode & RTLD_GLOBAL))
1916 revert_syms(orig_syms_tail);
1918 /* Processing of deferred lazy relocations must not happen until
1919 * the new libraries are committed; otherwise we could end up with
1920 * relocations resolved to symbol definitions that get removed. */
1924 if (tls_cnt != orig_tls_cnt)
1931 pthread_rwlock_unlock(&lock);
1932 if (p) do_init_fini(orig_tail);
1933 pthread_setcancelstate(cs, 0);
1937 hidden int __dl_invalid_handle(void *h)
1940 for (p=head; p; p=p->next) if (h==p) return 0;
1941 error("Invalid library handle %p", (void *)h);
1945 static void *addr2dso(size_t a)
1949 if (DL_FDPIC) for (p=head; p; p=p->next) {
1951 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1954 for (p=head; p; p=p->next) {
1955 if (DL_FDPIC && p->loadmap) {
1956 for (i=0; i<p->loadmap->nsegs; i++) {
1957 if (a-p->loadmap->segs[i].p_vaddr
1958 < p->loadmap->segs[i].p_memsz)
1963 size_t phcnt = p->phnum;
1964 size_t entsz = p->phentsize;
1965 size_t base = (size_t)p->base;
1966 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
1967 if (ph->p_type != PT_LOAD) continue;
1968 if (a-base-ph->p_vaddr < ph->p_memsz)
1971 if (a-(size_t)p->map < p->map_len)
1978 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1981 uint32_t h = 0, gh = 0, *ght;
1983 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1984 if (p == RTLD_DEFAULT) {
1986 } else if (p == RTLD_NEXT) {
1987 p = addr2dso((size_t)ra);
1991 struct symdef def = find_sym(p, s, 0);
1992 if (!def.sym) goto failed;
1993 if ((def.sym->st_info&0xf) == STT_TLS)
1994 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
1995 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
1996 return def.dso->funcdescs + (def.sym - def.dso->syms);
1997 return laddr(def.dso, def.sym->st_value);
1999 if (__dl_invalid_handle(p))
2001 if ((ght = p->ghashtab)) {
2003 sym = gnu_lookup(gh, ght, p, s);
2006 sym = sysv_lookup(s, h, p);
2008 if (sym && (sym->st_info&0xf) == STT_TLS)
2009 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
2010 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2011 return p->funcdescs + (sym - p->syms);
2012 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2013 return laddr(p, sym->st_value);
2014 for (i=0; p->deps[i]; i++) {
2015 if ((ght = p->deps[i]->ghashtab)) {
2016 if (!gh) gh = gnu_hash(s);
2017 sym = gnu_lookup(gh, ght, p->deps[i], s);
2019 if (!h) h = sysv_hash(s);
2020 sym = sysv_lookup(s, h, p->deps[i]);
2022 if (sym && (sym->st_info&0xf) == STT_TLS)
2023 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
2024 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
2025 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
2026 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
2027 return laddr(p->deps[i], sym->st_value);
2030 error("Symbol not found: %s", s);
2034 int dladdr(const void *addr_arg, Dl_info *info)
2036 size_t addr = (size_t)addr_arg;
2042 size_t besterr = -1;
2044 pthread_rwlock_rdlock(&lock);
2046 pthread_rwlock_unlock(&lock);
2051 strings = p->strings;
2052 nsym = count_syms(p);
2055 size_t idx = (addr-(size_t)p->funcdescs)
2056 / sizeof(*p->funcdescs);
2057 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2058 best = (size_t)(p->funcdescs + idx);
2059 bestsym = sym + idx;
2064 if (!best) for (; nsym; nsym--, sym++) {
2066 && (1<<(sym->st_info&0xf) & OK_TYPES)
2067 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2068 size_t symaddr = (size_t)laddr(p, sym->st_value);
2069 if (symaddr > addr || symaddr <= best)
2073 besterr = addr - symaddr;
2074 if (addr == symaddr)
2079 if (bestsym && besterr > bestsym->st_size-1) {
2084 info->dli_fname = p->name;
2085 info->dli_fbase = p->map;
2088 info->dli_sname = 0;
2089 info->dli_saddr = 0;
2093 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2094 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2095 info->dli_sname = strings + bestsym->st_name;
2096 info->dli_saddr = (void *)best;
2101 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2104 pthread_rwlock_rdlock(&lock);
2105 res = do_dlsym(p, s, ra);
2106 pthread_rwlock_unlock(&lock);
2110 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2112 struct dso *current;
2113 struct dl_phdr_info info;
2115 for(current = head; current;) {
2116 info.dlpi_addr = (uintptr_t)current->base;
2117 info.dlpi_name = current->name;
2118 info.dlpi_phdr = current->phdr;
2119 info.dlpi_phnum = current->phnum;
2120 info.dlpi_adds = gencnt;
2122 info.dlpi_tls_modid = current->tls_id;
2123 info.dlpi_tls_data = current->tls.image;
2125 ret = (callback)(&info, sizeof (info), data);
2127 if (ret != 0) break;
2129 pthread_rwlock_rdlock(&lock);
2130 current = current->next;
2131 pthread_rwlock_unlock(&lock);
2136 static void error(const char *fmt, ...)
2141 vdprintf(2, fmt, ap);
2147 __dl_vseterr(fmt, ap);