nsz Git - musl/blob - src/ldso/dynlink.c

   1 #define _GNU_SOURCE
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <stdarg.h>
   5 #include <stddef.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <stdint.h>
   9 #include <elf.h>
  10 #include <sys/mman.h>
  11 #include <limits.h>
  12 #include <fcntl.h>
  13 #include <sys/stat.h>
  14 #include <errno.h>
  15 #include <link.h>
  16 #include <setjmp.h>
  17 #include <pthread.h>
  18 #include <ctype.h>
  19 #include <dlfcn.h>
  20 #include "pthread_impl.h"
  21 #include "libc.h"
  22 #include "dynlink.h"
  23
  24 static void error(const char *, ...);
  25
  26 #ifdef SHARED
  27
  28 #define MAXP2(a,b) (-(-(a)&-(b)))
  29 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
  30
  31 struct debug {
  32         int ver;
  33         void *head;
  34         void (*bp)(void);
  35         int state;
  36         void *base;
  37 };
  38
  39 struct td_index {
  40         size_t args[2];
  41         struct td_index *next;
  42 };
  43
  44 struct dso {
  45         unsigned char *base;
  46         char *name;
  47         size_t *dynv;
  48         struct dso *next, *prev;
  49
  50         Phdr *phdr;
  51         int phnum;
  52         size_t phentsize;
  53         int refcnt;
  54         Sym *syms;
  55         uint32_t *hashtab;
  56         uint32_t *ghashtab;
  57         int16_t *versym;
  58         char *strings;
  59         unsigned char *map;
  60         size_t map_len;
  61         dev_t dev;
  62         ino_t ino;
  63         signed char global;
  64         char relocated;
  65         char constructed;
  66         char kernel_mapped;
  67         struct dso **deps, *needed_by;
  68         char *rpath_orig, *rpath;
  69         void *tls_image;
  70         size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
  71         size_t relro_start, relro_end;
  72         void **new_dtv;
  73         unsigned char *new_tls;
  74         volatile int new_dtv_idx, new_tls_idx;
  75         struct td_index *td_index;
  76         struct dso *fini_next;
  77         int rel_early_relative, rel_update_got;
  78         char *shortname;
  79         char buf[];
  80 };
  81
  82 struct symdef {
  83         Sym *sym;
  84         struct dso *dso;
  85 };
  86
  87 int __init_tp(void *);
  88 void __init_libc(char **, char *);
  89
  90 const char *__libc_get_version(void);
  91
  92 static struct builtin_tls {
  93         char c;
  94         struct pthread pt;
  95         void *space[16];
  96 } builtin_tls[1];
  97 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
  98
  99 static struct dso ldso;
 100 static struct dso *head, *tail, *fini_head;
 101 static char *env_path, *sys_path;
 102 static unsigned long long gencnt;
 103 static int runtime;
 104 static int ldd_mode;
 105 static int ldso_fail;
 106 static int noload;
 107 static jmp_buf *rtld_fail;
 108 static pthread_rwlock_t lock;
 109 static struct debug debug;
 110 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
 111 static size_t static_tls_cnt;
 112 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
 113
 114 struct debug *_dl_debug_addr = &debug;
 115
 116 static int dl_strcmp(const char *l, const char *r)
 117 {
 118         for (; *l==*r && *l; l++, r++);
 119         return *(unsigned char *)l - *(unsigned char *)r;
 120 }
 121 #define strcmp(l,r) dl_strcmp(l,r)
 122
 123 static void decode_vec(size_t *v, size_t *a, size_t cnt)
 124 {
 125         size_t i;
 126         for (i=0; i<cnt; i++) a[i] = 0;
 127         for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
 128                 a[0] |= 1UL<<v[0];
 129                 a[v[0]] = v[1];
 130         }
 131 }
 132
 133 static int search_vec(size_t *v, size_t *r, size_t key)
 134 {
 135         for (; v[0]!=key; v+=2)
 136                 if (!v[0]) return 0;
 137         *r = v[1];
 138         return 1;
 139 }
 140
 141 static uint32_t sysv_hash(const char *s0)
 142 {
 143         const unsigned char *s = (void *)s0;
 144         uint_fast32_t h = 0;
 145         while (*s) {
 146                 h = 16*h + *s++;
 147                 h ^= h>>24 & 0xf0;
 148         }
 149         return h & 0xfffffff;
 150 }
 151
 152 static uint32_t gnu_hash(const char *s0)
 153 {
 154         const unsigned char *s = (void *)s0;
 155         uint_fast32_t h = 5381;
 156         for (; *s; s++)
 157                 h = h*33 + *s;
 158         return h;
 159 }
 160
 161 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
 162 {
 163         size_t i;
 164         Sym *syms = dso->syms;
 165         uint32_t *hashtab = dso->hashtab;
 166         char *strings = dso->strings;
 167         for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
 168                 if ((!dso->versym || dso->versym[i] >= 0)
 169                     && (!strcmp(s, strings+syms[i].st_name)))
 170                         return syms+i;
 171         }
 172         return 0;
 173 }
 174
 175 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
 176 {
 177         Sym *syms = dso->syms;
 178         char *strings = dso->strings;
 179         uint32_t *hashtab = dso->ghashtab;
 180         uint32_t nbuckets = hashtab[0];
 181         uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
 182         uint32_t h2;
 183         uint32_t *hashval;
 184         uint32_t i = buckets[h1 % nbuckets];
 185
 186         if (!i) return 0;
 187
 188         hashval = buckets + nbuckets + (i - hashtab[1]);
 189
 190         for (h1 |= 1; ; i++) {
 191                 h2 = *hashval++;
 192                 if ((!dso->versym || dso->versym[i] >= 0)
 193                     && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
 194                         return syms+i;
 195                 if (h2 & 1) break;
 196         }
 197
 198         return 0;
 199 }
 200
 201 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
 202 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
 203
 204 #ifndef ARCH_SYM_REJECT_UND
 205 #define ARCH_SYM_REJECT_UND(s) 0
 206 #endif
 207
 208 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
 209 {
 210         uint32_t h = 0, gh = 0;
 211         struct symdef def = {0};
 212         for (; dso; dso=dso->next) {
 213                 Sym *sym;
 214                 if (!dso->global) continue;
 215                 if (dso->ghashtab) {
 216                         if (!gh) gh = gnu_hash(s);
 217                         sym = gnu_lookup(s, gh, dso);
 218                 } else {
 219                         if (!h) h = sysv_hash(s);
 220                         sym = sysv_lookup(s, h, dso);
 221                 }
 222                 if (!sym) continue;
 223                 if (!sym->st_shndx)
 224                         if (need_def || (sym->st_info&0xf) == STT_TLS
 225                             || ARCH_SYM_REJECT_UND(sym))
 226                                 continue;
 227                 if (!sym->st_value)
 228                         if ((sym->st_info&0xf) != STT_TLS)
 229                                 continue;
 230                 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
 231                 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
 232
 233                 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
 234                 def.sym = sym;
 235                 def.dso = dso;
 236                 if (sym->st_info>>4 == STB_GLOBAL) break;
 237         }
 238         return def;
 239 }
 240
 241 __attribute__((__visibility__("hidden")))
 242 ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
 243
 244 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
 245 {
 246         unsigned char *base = dso->base;
 247         Sym *syms = dso->syms;
 248         char *strings = dso->strings;
 249         Sym *sym;
 250         const char *name;
 251         void *ctx;
 252         int type;
 253         int sym_index;
 254         struct symdef def;
 255         size_t *reloc_addr;
 256         size_t sym_val;
 257         size_t tls_val;
 258         size_t addend;
 259
 260         for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
 261                 if (dso->rel_early_relative && IS_RELATIVE(rel[1])) continue;
 262                 type = R_TYPE(rel[1]);
 263                 sym_index = R_SYM(rel[1]);
 264                 reloc_addr = (void *)(base + rel[0]);
 265                 if (sym_index) {
 266                         sym = syms + sym_index;
 267                         name = strings + sym->st_name;
 268                         ctx = type==REL_COPY ? head->next : head;
 269                         def = find_sym(ctx, name, type==REL_PLT);
 270                         if (!def.sym && (sym->st_shndx != SHN_UNDEF
 271                             || sym->st_info>>4 != STB_WEAK)) {
 272                                 error("Error relocating %s: %s: symbol not found",
 273                                         dso->name, name);
 274                                 if (runtime) longjmp(*rtld_fail, 1);
 275                                 continue;
 276                         }
 277                 } else {
 278                         sym = 0;
 279                         def.sym = 0;
 280                         def.dso = dso;
 281                 }
 282
 283                 int gotplt = (type == REL_GOT || type == REL_PLT);
 284                 if (dso->rel_update_got && !gotplt && stride==2) continue;
 285
 286                 addend = stride>2 ? rel[2]
 287                         : gotplt || type==REL_COPY ? 0
 288                         : *reloc_addr;
 289
 290                 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
 291                 tls_val = def.sym ? def.sym->st_value : 0;
 292
 293                 switch(type) {
 294                 case REL_NONE:
 295                         break;
 296                 case REL_OFFSET:
 297                         addend -= (size_t)reloc_addr;
 298                 case REL_SYMBOLIC:
 299                 case REL_GOT:
 300                 case REL_PLT:
 301                         *reloc_addr = sym_val + addend;
 302                         break;
 303                 case REL_RELATIVE:
 304                         *reloc_addr = (size_t)base + addend;
 305                         break;
 306                 case REL_SYM_OR_REL:
 307                         if (sym) *reloc_addr = sym_val + addend;
 308                         else *reloc_addr = (size_t)base + addend;
 309                         break;
 310                 case REL_COPY:
 311                         memcpy(reloc_addr, (void *)sym_val, sym->st_size);
 312                         break;
 313                 case REL_OFFSET32:
 314                         *(uint32_t *)reloc_addr = sym_val + addend
 315                                 - (size_t)reloc_addr;
 316                         break;
 317                 case REL_DTPMOD:
 318                         *reloc_addr = def.dso->tls_id;
 319                         break;
 320                 case REL_DTPOFF:
 321                         *reloc_addr = tls_val + addend;
 322                         break;
 323 #ifdef TLS_ABOVE_TP
 324                 case REL_TPOFF:
 325                         *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
 326                         break;
 327 #else
 328                 case REL_TPOFF:
 329                         *reloc_addr = tls_val - def.dso->tls_offset + addend;
 330                         break;
 331                 case REL_TPOFF_NEG:
 332                         *reloc_addr = def.dso->tls_offset - tls_val + addend;
 333                         break;
 334 #endif
 335                 case REL_TLSDESC:
 336                         if (stride<3) addend = reloc_addr[1];
 337                         if (runtime && def.dso->tls_id >= static_tls_cnt) {
 338                                 struct td_index *new = malloc(sizeof *new);
 339                                 if (!new) {
 340                                         error(
 341                                         "Error relocating %s: cannot allocate TLSDESC for %s",
 342                                         dso->name, sym ? name : "(local)" );
 343                                         longjmp(*rtld_fail, 1);
 344                                 }
 345                                 new->next = dso->td_index;
 346                                 dso->td_index = new;
 347                                 new->args[0] = def.dso->tls_id;
 348                                 new->args[1] = tls_val + addend;
 349                                 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
 350                                 reloc_addr[1] = (size_t)new;
 351                         } else {
 352                                 reloc_addr[0] = (size_t)__tlsdesc_static;
 353 #ifdef TLS_ABOVE_TP
 354                                 reloc_addr[1] = tls_val + def.dso->tls_offset
 355                                         + TPOFF_K + addend;
 356 #else
 357                                 reloc_addr[1] = tls_val - def.dso->tls_offset
 358                                         + addend;
 359 #endif
 360                         }
 361                         break;
 362                 default:
 363                         error("Error relocating %s: unsupported relocation type %d",
 364                                 dso->name, type);
 365                         if (runtime) longjmp(*rtld_fail, 1);
 366                         continue;
 367                 }
 368         }
 369 }
 370
 371 /* A huge hack: to make up for the wastefulness of shared libraries
 372  * needing at least a page of dirty memory even if they have no global
 373  * data, we reclaim the gaps at the beginning and end of writable maps
 374  * and "donate" them to the heap by setting up minimal malloc
 375  * structures and then freeing them. */
 376
 377 static void reclaim(struct dso *dso, size_t start, size_t end)
 378 {
 379         size_t *a, *z;
 380         if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
 381         if (end   >= dso->relro_start && end   < dso->relro_end) end = dso->relro_start;
 382         start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
 383         end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
 384         if (start>end || end-start < 4*sizeof(size_t)) return;
 385         a = (size_t *)(dso->base + start);
 386         z = (size_t *)(dso->base + end);
 387         a[-2] = 1;
 388         a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
 389         z[1] = 1;
 390         free(a);
 391 }
 392
 393 static void reclaim_gaps(struct dso *dso)
 394 {
 395         Phdr *ph = dso->phdr;
 396         size_t phcnt = dso->phnum;
 397
 398         for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
 399                 if (ph->p_type!=PT_LOAD) continue;
 400                 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
 401                 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
 402                 reclaim(dso, ph->p_vaddr+ph->p_memsz,
 403                         ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
 404         }
 405 }
 406
 407 static void *map_library(int fd, struct dso *dso)
 408 {
 409         Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
 410         void *allocated_buf=0;
 411         size_t phsize;
 412         size_t addr_min=SIZE_MAX, addr_max=0, map_len;
 413         size_t this_min, this_max;
 414         off_t off_start;
 415         Ehdr *eh;
 416         Phdr *ph, *ph0;
 417         unsigned prot;
 418         unsigned char *map=MAP_FAILED, *base;
 419         size_t dyn=0;
 420         size_t tls_image=0;
 421         size_t i;
 422
 423         ssize_t l = read(fd, buf, sizeof buf);
 424         eh = buf;
 425         if (l<0) return 0;
 426         if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
 427                 goto noexec;
 428         phsize = eh->e_phentsize * eh->e_phnum;
 429         if (phsize > sizeof buf - sizeof *eh) {
 430                 allocated_buf = malloc(phsize);
 431                 if (!allocated_buf) return 0;
 432                 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
 433                 if (l < 0) goto error;
 434                 if (l != phsize) goto noexec;
 435                 ph = ph0 = allocated_buf;
 436         } else if (eh->e_phoff + phsize > l) {
 437                 l = pread(fd, buf+1, phsize, eh->e_phoff);
 438                 if (l < 0) goto error;
 439                 if (l != phsize) goto noexec;
 440                 ph = ph0 = (void *)(buf + 1);
 441         } else {
 442                 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
 443         }
 444         for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 445                 if (ph->p_type == PT_DYNAMIC) {
 446                         dyn = ph->p_vaddr;
 447                 } else if (ph->p_type == PT_TLS) {
 448                         tls_image = ph->p_vaddr;
 449                         dso->tls_align = ph->p_align;
 450                         dso->tls_len = ph->p_filesz;
 451                         dso->tls_size = ph->p_memsz;
 452                 } else if (ph->p_type == PT_GNU_RELRO) {
 453                         dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
 454                         dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 455                 }
 456                 if (ph->p_type != PT_LOAD) continue;
 457                 if (ph->p_vaddr < addr_min) {
 458                         addr_min = ph->p_vaddr;
 459                         off_start = ph->p_offset;
 460                         prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 461                                 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 462                                 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 463                 }
 464                 if (ph->p_vaddr+ph->p_memsz > addr_max) {
 465                         addr_max = ph->p_vaddr+ph->p_memsz;
 466                 }
 467         }
 468         if (!dyn) goto noexec;
 469         addr_max += PAGE_SIZE-1;
 470         addr_max &= -PAGE_SIZE;
 471         addr_min &= -PAGE_SIZE;
 472         off_start &= -PAGE_SIZE;
 473         map_len = addr_max - addr_min + off_start;
 474         /* The first time, we map too much, possibly even more than
 475          * the length of the file. This is okay because we will not
 476          * use the invalid part; we just need to reserve the right
 477          * amount of virtual address space to map over later. */
 478         map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
 479         if (map==MAP_FAILED) goto error;
 480         /* If the loaded file is not relocatable and the requested address is
 481          * not available, then the load operation must fail. */
 482         if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
 483                 errno = EBUSY;
 484                 goto error;
 485         }
 486         base = map - addr_min;
 487         dso->phdr = 0;
 488         dso->phnum = 0;
 489         for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
 490                 if (ph->p_type != PT_LOAD) continue;
 491                 /* Check if the programs headers are in this load segment, and
 492                  * if so, record the address for use by dl_iterate_phdr. */
 493                 if (!dso->phdr && eh->e_phoff >= ph->p_offset
 494                     && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
 495                         dso->phdr = (void *)(base + ph->p_vaddr
 496                                 + (eh->e_phoff-ph->p_offset));
 497                         dso->phnum = eh->e_phnum;
 498                         dso->phentsize = eh->e_phentsize;
 499                 }
 500                 /* Reuse the existing mapping for the lowest-address LOAD */
 501                 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
 502                 this_min = ph->p_vaddr & -PAGE_SIZE;
 503                 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
 504                 off_start = ph->p_offset & -PAGE_SIZE;
 505                 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
 506                         ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
 507                         ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
 508                 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
 509                         goto error;
 510                 if (ph->p_memsz > ph->p_filesz) {
 511                         size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
 512                         size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
 513                         memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
 514                         if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
 515                                 goto error;
 516                 }
 517         }
 518         for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
 519                 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
 520                         if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
 521                                 goto error;
 522                         break;
 523                 }
 524         dso->map = map;
 525         dso->map_len = map_len;
 526         dso->base = base;
 527         dso->dynv = (void *)(base+dyn);
 528         if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
 529         if (!runtime) reclaim_gaps(dso);
 530         free(allocated_buf);
 531         return map;
 532 noexec:
 533         errno = ENOEXEC;
 534 error:
 535         if (map!=MAP_FAILED) munmap(map, map_len);
 536         free(allocated_buf);
 537         return 0;
 538 }
 539
 540 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
 541 {
 542         size_t l;
 543         int fd;
 544         for (;;) {
 545                 s += strspn(s, ":\n");
 546                 l = strcspn(s, ":\n");
 547                 if (l-1 >= INT_MAX) return -1;
 548                 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
 549                         if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
 550                         switch (errno) {
 551                         case ENOENT:
 552                         case ENOTDIR:
 553                         case EACCES:
 554                         case ENAMETOOLONG:
 555                                 break;
 556                         default:
 557                                 /* Any negative value but -1 will inhibit
 558                                  * futher path search. */
 559                                 return -2;
 560                         }
 561                 }
 562                 s += l;
 563         }
 564 }
 565
 566 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
 567 {
 568         size_t n, l;
 569         const char *s, *t, *origin;
 570         char *d;
 571         if (p->rpath || !p->rpath_orig) return 0;
 572         if (!strchr(p->rpath_orig, '$')) {
 573                 p->rpath = p->rpath_orig;
 574                 return 0;
 575         }
 576         n = 0;
 577         s = p->rpath_orig;
 578         while ((t=strchr(s, '$'))) {
 579                 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
 580                         return 0;
 581                 s = t+1;
 582                 n++;
 583         }
 584         if (n > SSIZE_MAX/PATH_MAX) return 0;
 585
 586         if (p->kernel_mapped) {
 587                 /* $ORIGIN searches cannot be performed for the main program
 588                  * when it is suid/sgid/AT_SECURE. This is because the
 589                  * pathname is under the control of the caller of execve.
 590                  * For libraries, however, $ORIGIN can be processed safely
 591                  * since the library's pathname came from a trusted source
 592                  * (either system paths or a call to dlopen). */
 593                 if (libc.secure)
 594                         return 0;
 595                 l = readlink("/proc/self/exe", buf, buf_size);
 596                 if (l == -1) switch (errno) {
 597                 case ENOENT:
 598                 case ENOTDIR:
 599                 case EACCES:
 600                         break;
 601                 default:
 602                         return -1;
 603                 }
 604                 if (l >= buf_size)
 605                         return 0;
 606                 buf[l] = 0;
 607                 origin = buf;
 608         } else {
 609                 origin = p->name;
 610         }
 611         t = strrchr(origin, '/');
 612         l = t ? t-origin : 0;
 613         p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
 614         if (!p->rpath) return -1;
 615
 616         d = p->rpath;
 617         s = p->rpath_orig;
 618         while ((t=strchr(s, '$'))) {
 619                 memcpy(d, s, t-s);
 620                 d += t-s;
 621                 memcpy(d, origin, l);
 622                 d += l;
 623                 /* It was determined previously that the '$' is followed
 624                  * either by "ORIGIN" or "{ORIGIN}". */
 625                 s = t + 7 + 2*(t[1]=='{');
 626         }
 627         strcpy(d, s);
 628         return 0;
 629 }
 630
 631 static void decode_dyn(struct dso *p)
 632 {
 633         size_t dyn[DYN_CNT];
 634         decode_vec(p->dynv, dyn, DYN_CNT);
 635         p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
 636         p->strings = (void *)(p->base + dyn[DT_STRTAB]);
 637         if (dyn[0]&(1<<DT_HASH))
 638                 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
 639         if (dyn[0]&(1<<DT_RPATH))
 640                 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
 641         if (dyn[0]&(1<<DT_RUNPATH))
 642                 p->rpath_orig = (void *)(p->strings + dyn[DT_RUNPATH]);
 643         if (search_vec(p->dynv, dyn, DT_GNU_HASH))
 644                 p->ghashtab = (void *)(p->base + *dyn);
 645         if (search_vec(p->dynv, dyn, DT_VERSYM))
 646                 p->versym = (void *)(p->base + *dyn);
 647 }
 648
 649 static struct dso *load_library(const char *name, struct dso *needed_by)
 650 {
 651         char buf[2*NAME_MAX+2];
 652         const char *pathname;
 653         unsigned char *map;
 654         struct dso *p, temp_dso = {0};
 655         int fd;
 656         struct stat st;
 657         size_t alloc_size;
 658         int n_th = 0;
 659         int is_self = 0;
 660
 661         if (!*name) {
 662                 errno = EINVAL;
 663                 return 0;
 664         }
 665
 666         /* Catch and block attempts to reload the implementation itself */
 667         if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
 668                 static const char *rp, reserved[] =
 669                         "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
 670                 char *z = strchr(name, '.');
 671                 if (z) {
 672                         size_t l = z-name;
 673                         for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
 674                         if (*rp) {
 675                                 if (ldd_mode) {
 676                                         /* Track which names have been resolved
 677                                          * and only report each one once. */
 678                                         static unsigned reported;
 679                                         unsigned mask = 1U<<(rp-reserved);
 680                                         if (!(reported & mask)) {
 681                                                 reported |= mask;
 682                                                 dprintf(1, "\t%s => %s (%p)\n",
 683                                                         name, ldso.name,
 684                                                         ldso.base);
 685                                         }
 686                                 }
 687                                 is_self = 1;
 688                         }
 689                 }
 690         }
 691         if (!strcmp(name, ldso.name)) is_self = 1;
 692         if (is_self) {
 693                 if (!ldso.prev) {
 694                         tail->next = &ldso;
 695                         ldso.prev = tail;
 696                         tail = ldso.next ? ldso.next : &ldso;
 697                 }
 698                 return &ldso;
 699         }
 700         if (strchr(name, '/')) {
 701                 pathname = name;
 702                 fd = open(name, O_RDONLY|O_CLOEXEC);
 703         } else {
 704                 /* Search for the name to see if it's already loaded */
 705                 for (p=head->next; p; p=p->next) {
 706                         if (p->shortname && !strcmp(p->shortname, name)) {
 707                                 p->refcnt++;
 708                                 return p;
 709                         }
 710                 }
 711                 if (strlen(name) > NAME_MAX) return 0;
 712                 fd = -1;
 713                 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
 714                 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
 715                         if (fixup_rpath(p, buf, sizeof buf) < 0)
 716                                 fd = -2; /* Inhibit further search. */
 717                         if (p->rpath)
 718                                 fd = path_open(name, p->rpath, buf, sizeof buf);
 719                 }
 720                 if (fd == -1) {
 721                         if (!sys_path) {
 722                                 char *prefix = 0;
 723                                 size_t prefix_len;
 724                                 if (ldso.name[0]=='/') {
 725                                         char *s, *t, *z;
 726                                         for (s=t=z=ldso.name; *s; s++)
 727                                                 if (*s=='/') z=t, t=s;
 728                                         prefix_len = z-ldso.name;
 729                                         if (prefix_len < PATH_MAX)
 730                                                 prefix = ldso.name;
 731                                 }
 732                                 if (!prefix) {
 733                                         prefix = "";
 734                                         prefix_len = 0;
 735                                 }
 736                                 char etc_ldso_path[prefix_len + 1
 737                                         + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
 738                                 snprintf(etc_ldso_path, sizeof etc_ldso_path,
 739                                         "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
 740                                         (int)prefix_len, prefix);
 741                                 FILE *f = fopen(etc_ldso_path, "rbe");
 742                                 if (f) {
 743                                         if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
 744                                                 free(sys_path);
 745                                                 sys_path = "";
 746                                         }
 747                                         fclose(f);
 748                                 } else if (errno != ENOENT) {
 749                                         sys_path = "";
 750                                 }
 751                         }
 752                         if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
 753                         fd = path_open(name, sys_path, buf, sizeof buf);
 754                 }
 755                 pathname = buf;
 756         }
 757         if (fd < 0) return 0;
 758         if (fstat(fd, &st) < 0) {
 759                 close(fd);
 760                 return 0;
 761         }
 762         for (p=head->next; p; p=p->next) {
 763                 if (p->dev == st.st_dev && p->ino == st.st_ino) {
 764                         /* If this library was previously loaded with a
 765                          * pathname but a search found the same inode,
 766                          * setup its shortname so it can be found by name. */
 767                         if (!p->shortname && pathname != name)
 768                                 p->shortname = strrchr(p->name, '/')+1;
 769                         close(fd);
 770                         p->refcnt++;
 771                         return p;
 772                 }
 773         }
 774         map = noload ? 0 : map_library(fd, &temp_dso);
 775         close(fd);
 776         if (!map) return 0;
 777
 778         /* Allocate storage for the new DSO. When there is TLS, this
 779          * storage must include a reservation for all pre-existing
 780          * threads to obtain copies of both the new TLS, and an
 781          * extended DTV capable of storing an additional slot for
 782          * the newly-loaded DSO. */
 783         alloc_size = sizeof *p + strlen(pathname) + 1;
 784         if (runtime && temp_dso.tls_image) {
 785                 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
 786                         + sizeof(void *) * (tls_cnt+3);
 787                 n_th = libc.threads_minus_1 + 1;
 788                 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
 789                 else alloc_size += n_th * per_th;
 790         }
 791         p = calloc(1, alloc_size);
 792         if (!p) {
 793                 munmap(map, temp_dso.map_len);
 794                 return 0;
 795         }
 796         memcpy(p, &temp_dso, sizeof temp_dso);
 797         decode_dyn(p);
 798         p->dev = st.st_dev;
 799         p->ino = st.st_ino;
 800         p->refcnt = 1;
 801         p->needed_by = needed_by;
 802         p->name = p->buf;
 803         strcpy(p->name, pathname);
 804         /* Add a shortname only if name arg was not an explicit pathname. */
 805         if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
 806         if (p->tls_image) {
 807                 p->tls_id = ++tls_cnt;
 808                 tls_align = MAXP2(tls_align, p->tls_align);
 809 #ifdef TLS_ABOVE_TP
 810                 p->tls_offset = tls_offset + ( (tls_align-1) &
 811                         -(tls_offset + (uintptr_t)p->tls_image) );
 812                 tls_offset += p->tls_size;
 813 #else
 814                 tls_offset += p->tls_size + p->tls_align - 1;
 815                 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
 816                         & (p->tls_align-1);
 817                 p->tls_offset = tls_offset;
 818 #endif
 819                 p->new_dtv = (void *)(-sizeof(size_t) &
 820                         (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
 821                 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
 822         }
 823
 824         tail->next = p;
 825         p->prev = tail;
 826         tail = p;
 827
 828         if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
 829
 830         return p;
 831 }
 832
 833 static void load_deps(struct dso *p)
 834 {
 835         size_t i, ndeps=0;
 836         struct dso ***deps = &p->deps, **tmp, *dep;
 837         for (; p; p=p->next) {
 838                 for (i=0; p->dynv[i]; i+=2) {
 839                         if (p->dynv[i] != DT_NEEDED) continue;
 840                         dep = load_library(p->strings + p->dynv[i+1], p);
 841                         if (!dep) {
 842                                 error("Error loading shared library %s: %m (needed by %s)",
 843                                         p->strings + p->dynv[i+1], p->name);
 844                                 if (runtime) longjmp(*rtld_fail, 1);
 845                                 continue;
 846                         }
 847                         if (runtime) {
 848                                 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
 849                                 if (!tmp) longjmp(*rtld_fail, 1);
 850                                 tmp[ndeps++] = dep;
 851                                 tmp[ndeps] = 0;
 852                                 *deps = tmp;
 853                         }
 854                 }
 855         }
 856 }
 857
 858 static void load_preload(char *s)
 859 {
 860         int tmp;
 861         char *z;
 862         for (z=s; *z; s=z) {
 863                 for (   ; *s && (isspace(*s) || *s==':'); s++);
 864                 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
 865                 tmp = *z;
 866                 *z = 0;
 867                 load_library(s, 0);
 868                 *z = tmp;
 869         }
 870 }
 871
 872 static void make_global(struct dso *p)
 873 {
 874         for (; p; p=p->next) p->global = 1;
 875 }
 876
 877 static void do_mips_relocs(struct dso *p, size_t *got)
 878 {
 879         size_t i, j, rel[2];
 880         unsigned char *base = p->base;
 881         i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
 882         if (p->rel_early_relative) {
 883                 got += i;
 884         } else {
 885                 while (i--) *got++ += (size_t)base;
 886         }
 887         j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
 888         i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
 889         Sym *sym = p->syms + j;
 890         rel[0] = (unsigned char *)got - base;
 891         for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
 892                 rel[1] = sym-p->syms << 8 | R_MIPS_JUMP_SLOT;
 893                 do_relocs(p, rel, sizeof rel, 2);
 894         }
 895 }
 896
 897 static void reloc_all(struct dso *p)
 898 {
 899         size_t dyn[DYN_CNT];
 900         for (; p; p=p->next) {
 901                 if (p->relocated) continue;
 902                 decode_vec(p->dynv, dyn, DYN_CNT);
 903                 if (NEED_MIPS_GOT_RELOCS)
 904                         do_mips_relocs(p, (void *)(p->base+dyn[DT_PLTGOT]));
 905                 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
 906                         2+(dyn[DT_PLTREL]==DT_RELA));
 907                 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
 908                 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
 909
 910                 if (head != &ldso && p->relro_start != p->relro_end &&
 911                     mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
 912                         error("Error relocating %s: RELRO protection failed: %m",
 913                                 p->name);
 914                         if (runtime) longjmp(*rtld_fail, 1);
 915                 }
 916
 917                 p->relocated = 1;
 918         }
 919 }
 920
 921 static void kernel_mapped_dso(struct dso *p)
 922 {
 923         size_t min_addr = -1, max_addr = 0, cnt;
 924         Phdr *ph = p->phdr;
 925         for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
 926                 if (ph->p_type == PT_DYNAMIC) {
 927                         p->dynv = (void *)(p->base + ph->p_vaddr);
 928                 } else if (ph->p_type == PT_GNU_RELRO) {
 929                         p->relro_start = ph->p_vaddr & -PAGE_SIZE;
 930                         p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
 931                 }
 932                 if (ph->p_type != PT_LOAD) continue;
 933                 if (ph->p_vaddr < min_addr)
 934                         min_addr = ph->p_vaddr;
 935                 if (ph->p_vaddr+ph->p_memsz > max_addr)
 936                         max_addr = ph->p_vaddr+ph->p_memsz;
 937         }
 938         min_addr &= -PAGE_SIZE;
 939         max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
 940         p->map = p->base + min_addr;
 941         p->map_len = max_addr - min_addr;
 942         p->kernel_mapped = 1;
 943 }
 944
 945 static void do_fini()
 946 {
 947         struct dso *p;
 948         size_t dyn[DYN_CNT];
 949         for (p=fini_head; p; p=p->fini_next) {
 950                 if (!p->constructed) continue;
 951                 decode_vec(p->dynv, dyn, DYN_CNT);
 952                 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
 953                         size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
 954                         size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
 955                         while (n--) ((void (*)(void))*--fn)();
 956                 }
 957 #ifndef NO_LEGACY_INITFINI
 958                 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
 959                         ((void (*)(void))(p->base + dyn[DT_FINI]))();
 960 #endif
 961         }
 962 }
 963
 964 static void do_init_fini(struct dso *p)
 965 {
 966         size_t dyn[DYN_CNT];
 967         int need_locking = libc.threads_minus_1;
 968         /* Allow recursive calls that arise when a library calls
 969          * dlopen from one of its constructors, but block any
 970          * other threads until all ctors have finished. */
 971         if (need_locking) pthread_mutex_lock(&init_fini_lock);
 972         for (; p; p=p->prev) {
 973                 if (p->constructed) continue;
 974                 p->constructed = 1;
 975                 decode_vec(p->dynv, dyn, DYN_CNT);
 976                 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
 977                         p->fini_next = fini_head;
 978                         fini_head = p;
 979                 }
 980 #ifndef NO_LEGACY_INITFINI
 981                 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
 982                         ((void (*)(void))(p->base + dyn[DT_INIT]))();
 983 #endif
 984                 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
 985                         size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
 986                         size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
 987                         while (n--) ((void (*)(void))*fn++)();
 988                 }
 989                 if (!need_locking && libc.threads_minus_1) {
 990                         need_locking = 1;
 991                         pthread_mutex_lock(&init_fini_lock);
 992                 }
 993         }
 994         if (need_locking) pthread_mutex_unlock(&init_fini_lock);
 995 }
 996
 997 static void dl_debug_state(void)
 998 {
 999 }
1000
1001 weak_alias(dl_debug_state, _dl_debug_state);
1002
1003 void __reset_tls()
1004 {
1005         pthread_t self = __pthread_self();
1006         struct dso *p;
1007         for (p=head; p; p=p->next) {
1008                 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
1009                 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
1010                 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
1011                         p->tls_size - p->tls_len);
1012                 if (p->tls_id == (size_t)self->dtv[0]) break;
1013         }
1014 }
1015
1016 void *__copy_tls(unsigned char *mem)
1017 {
1018         pthread_t td;
1019         struct dso *p;
1020         void **dtv;
1021
1022 #ifdef TLS_ABOVE_TP
1023         dtv = (void **)(mem + libc.tls_size) - (tls_cnt + 1);
1024
1025         mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
1026         td = (pthread_t)mem;
1027         mem += sizeof(struct pthread);
1028
1029         for (p=head; p; p=p->next) {
1030                 if (!p->tls_id) continue;
1031                 dtv[p->tls_id] = mem + p->tls_offset;
1032                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1033         }
1034 #else
1035         dtv = (void **)mem;
1036
1037         mem += libc.tls_size - sizeof(struct pthread);
1038         mem -= (uintptr_t)mem & (tls_align-1);
1039         td = (pthread_t)mem;
1040
1041         for (p=head; p; p=p->next) {
1042                 if (!p->tls_id) continue;
1043                 dtv[p->tls_id] = mem - p->tls_offset;
1044                 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1045         }
1046 #endif
1047         dtv[0] = (void *)tls_cnt;
1048         td->dtv = td->dtv_copy = dtv;
1049         return td;
1050 }
1051
1052 __attribute__((__visibility__("hidden")))
1053 void *__tls_get_new(size_t *v)
1054 {
1055         pthread_t self = __pthread_self();
1056
1057         /* Block signals to make accessing new TLS async-signal-safe */
1058         sigset_t set;
1059         __block_all_sigs(&set);
1060         if (v[0]<=(size_t)self->dtv[0]) {
1061                 __restore_sigs(&set);
1062                 return (char *)self->dtv[v[0]]+v[1];
1063         }
1064
1065         /* This is safe without any locks held because, if the caller
1066          * is able to request the Nth entry of the DTV, the DSO list
1067          * must be valid at least that far out and it was synchronized
1068          * at program startup or by an already-completed call to dlopen. */
1069         struct dso *p;
1070         for (p=head; p->tls_id != v[0]; p=p->next);
1071
1072         /* Get new DTV space from new DSO if needed */
1073         if (v[0] > (size_t)self->dtv[0]) {
1074                 void **newdtv = p->new_dtv +
1075                         (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1076                 memcpy(newdtv, self->dtv,
1077                         ((size_t)self->dtv[0]+1) * sizeof(void *));
1078                 newdtv[0] = (void *)v[0];
1079                 self->dtv = self->dtv_copy = newdtv;
1080         }
1081
1082         /* Get new TLS memory from all new DSOs up to the requested one */
1083         unsigned char *mem;
1084         for (p=head; ; p=p->next) {
1085                 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1086                 mem = p->new_tls + (p->tls_size + p->tls_align)
1087                         * a_fetch_add(&p->new_tls_idx,1);
1088                 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
1089                         & (p->tls_align-1);
1090                 self->dtv[p->tls_id] = mem;
1091                 memcpy(mem, p->tls_image, p->tls_len);
1092                 if (p->tls_id == v[0]) break;
1093         }
1094         __restore_sigs(&set);
1095         return mem + v[1];
1096 }
1097
1098 static void update_tls_size()
1099 {
1100         libc.tls_size = ALIGN(
1101                 (1+tls_cnt) * sizeof(void *) +
1102                 tls_offset +
1103                 sizeof(struct pthread) +
1104                 tls_align * 2,
1105         tls_align);
1106 }
1107
1108 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1109  * following stage 2 and stage 3 functions via primitive symbolic lookup
1110  * since it does not have access to their addresses to begin with. */
1111
1112 /* Stage 2 of the dynamic linker is called after relative relocations
1113  * have been processed. It can make function calls to static functions
1114  * and access string literals and static data, but cannot use extern
1115  * symbols. Its job is to perform symbolic relocations on the dynamic
1116  * linker itself, but some of the relocations performed may need to be
1117  * replaced later due to copy relocations in the main program. */
1118
1119 void __dls2(unsigned char *base, size_t *sp)
1120 {
1121         Ehdr *ehdr = (void *)base;
1122         ldso.base = base;
1123         ldso.name = ldso.shortname = "libc.so";
1124         ldso.global = 1;
1125         ldso.phnum = ehdr->e_phnum;
1126         ldso.phdr = (void *)(base + ehdr->e_phoff);
1127         ldso.phentsize = ehdr->e_phentsize;
1128         ldso.rel_early_relative = 1;
1129         kernel_mapped_dso(&ldso);
1130         decode_dyn(&ldso);
1131
1132         head = &ldso;
1133         reloc_all(&ldso);
1134
1135         ldso.relocated = 0;
1136         ldso.rel_update_got = 1;
1137
1138         /* Call dynamic linker stage-3, __dls3, looking it up
1139          * symbolically as a barrier against moving the address
1140          * load across the above relocation processing. */
1141         struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1142         ((stage3_func)(ldso.base+dls3_def.sym->st_value))(sp);
1143 }
1144
1145 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1146  * fully functional. Its job is to load (if not already loaded) and
1147  * process dependencies and relocations for the main application and
1148  * transfer control to its entry point. */
1149
1150 _Noreturn void __dls3(size_t *sp)
1151 {
1152         static struct dso app, vdso;
1153         size_t aux[AUX_CNT], *auxv;
1154         size_t i;
1155         char *env_preload=0;
1156         size_t vdso_base;
1157         int argc = *sp;
1158         char **argv = (void *)(sp+1);
1159         char **argv_orig = argv;
1160         char **envp = argv+argc+1;
1161
1162         /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1163          * use during dynamic linking. If possible it will also serve as the
1164          * thread pointer at runtime. */
1165         libc.tls_size = sizeof builtin_tls;
1166         if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1167                 a_crash();
1168         }
1169
1170         /* Find aux vector just past environ[] */
1171         for (i=argc+1; argv[i]; i++)
1172                 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
1173                         env_path = argv[i]+16;
1174                 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
1175                         env_preload = argv[i]+11;
1176         auxv = (void *)(argv+i+1);
1177
1178         decode_vec(auxv, aux, AUX_CNT);
1179
1180         /* Only trust user/env if kernel says we're not suid/sgid */
1181         if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1182           || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1183                 env_path = 0;
1184                 env_preload = 0;
1185                 libc.secure = 1;
1186         }
1187         libc.page_size = aux[AT_PAGESZ];
1188         libc.auxv = auxv;
1189
1190         /* If the main program was already loaded by the kernel,
1191          * AT_PHDR will point to some location other than the dynamic
1192          * linker's program headers. */
1193         if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1194                 size_t interp_off = 0;
1195                 size_t tls_image = 0;
1196                 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1197                 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1198                 app.phnum = aux[AT_PHNUM];
1199                 app.phentsize = aux[AT_PHENT];
1200                 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1201                         if (phdr->p_type == PT_PHDR)
1202                                 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1203                         else if (phdr->p_type == PT_INTERP)
1204                                 interp_off = (size_t)phdr->p_vaddr;
1205                         else if (phdr->p_type == PT_TLS) {
1206                                 tls_image = phdr->p_vaddr;
1207                                 app.tls_len = phdr->p_filesz;
1208                                 app.tls_size = phdr->p_memsz;
1209                                 app.tls_align = phdr->p_align;
1210                         }
1211                 }
1212                 if (app.tls_size) app.tls_image = (char *)app.base + tls_image;
1213                 if (interp_off) ldso.name = (char *)app.base + interp_off;
1214                 if ((aux[0] & (1UL<<AT_EXECFN))
1215                     && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1216                         app.name = (char *)aux[AT_EXECFN];
1217                 else
1218                         app.name = argv[0];
1219                 kernel_mapped_dso(&app);
1220         } else {
1221                 int fd;
1222                 char *ldname = argv[0];
1223                 size_t l = strlen(ldname);
1224                 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1225                 argv++;
1226                 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1227                         char *opt = argv[0]+2;
1228                         *argv++ = (void *)-1;
1229                         if (!*opt) {
1230                                 break;
1231                         } else if (!memcmp(opt, "list", 5)) {
1232                                 ldd_mode = 1;
1233                         } else if (!memcmp(opt, "library-path", 12)) {
1234                                 if (opt[12]=='=') env_path = opt+13;
1235                                 else if (opt[12]) *argv = 0;
1236                                 else if (*argv) env_path = *argv++;
1237                         } else if (!memcmp(opt, "preload", 7)) {
1238                                 if (opt[7]=='=') env_preload = opt+8;
1239                                 else if (opt[7]) *argv = 0;
1240                                 else if (*argv) env_preload = *argv++;
1241                         } else {
1242                                 argv[0] = 0;
1243                         }
1244                 }
1245                 argv[-1] = (void *)(argc - (argv-argv_orig));
1246                 if (!argv[0]) {
1247                         dprintf(2, "musl libc\n"
1248                                 "Version %s\n"
1249                                 "Dynamic Program Loader\n"
1250                                 "Usage: %s [options] [--] pathname%s\n",
1251                                 __libc_get_version(), ldname,
1252                                 ldd_mode ? "" : " [args]");
1253                         _exit(1);
1254                 }
1255                 fd = open(argv[0], O_RDONLY);
1256                 if (fd < 0) {
1257                         dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1258                         _exit(1);
1259                 }
1260                 runtime = 1;
1261                 Ehdr *ehdr = (void *)map_library(fd, &app);
1262                 if (!ehdr) {
1263                         dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1264                         _exit(1);
1265                 }
1266                 runtime = 0;
1267                 close(fd);
1268                 ldso.name = ldname;
1269                 app.name = argv[0];
1270                 aux[AT_ENTRY] = (size_t)app.base + ehdr->e_entry;
1271                 /* Find the name that would have been used for the dynamic
1272                  * linker had ldd not taken its place. */
1273                 if (ldd_mode) {
1274                         for (i=0; i<app.phnum; i++) {
1275                                 if (app.phdr[i].p_type == PT_INTERP)
1276                                         ldso.name = (void *)(app.base
1277                                                 + app.phdr[i].p_vaddr);
1278                         }
1279                         dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1280                 }
1281         }
1282         if (app.tls_size) {
1283                 app.tls_id = tls_cnt = 1;
1284 #ifdef TLS_ABOVE_TP
1285                 app.tls_offset = 0;
1286                 tls_offset = app.tls_size
1287                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1288                         & (app.tls_align-1) );
1289 #else
1290                 tls_offset = app.tls_offset = app.tls_size
1291                         + ( -((uintptr_t)app.tls_image + app.tls_size)
1292                         & (app.tls_align-1) );
1293 #endif
1294                 tls_align = MAXP2(tls_align, app.tls_align);
1295         }
1296         app.global = 1;
1297         decode_dyn(&app);
1298
1299         /* Attach to vdso, if provided by the kernel */
1300         if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1301                 Ehdr *ehdr = (void *)vdso_base;
1302                 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1303                 vdso.phnum = ehdr->e_phnum;
1304                 vdso.phentsize = ehdr->e_phentsize;
1305                 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1306                         if (phdr->p_type == PT_DYNAMIC)
1307                                 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1308                         if (phdr->p_type == PT_LOAD)
1309                                 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1310                 }
1311                 vdso.name = "";
1312                 vdso.shortname = "linux-gate.so.1";
1313                 vdso.global = 1;
1314                 vdso.relocated = 1;
1315                 decode_dyn(&vdso);
1316                 vdso.prev = &ldso;
1317                 ldso.next = &vdso;
1318         }
1319
1320         /* Initial dso chain consists only of the app. */
1321         head = tail = &app;
1322
1323         /* Donate unused parts of app and library mapping to malloc */
1324         reclaim_gaps(&app);
1325         reclaim_gaps(&ldso);
1326
1327         /* Load preload/needed libraries, add their symbols to the global
1328          * namespace, and perform all remaining relocations. */
1329         if (env_preload) load_preload(env_preload);
1330         load_deps(&app);
1331         make_global(&app);
1332
1333 #ifndef DYNAMIC_IS_RO
1334         for (i=0; app.dynv[i]; i+=2)
1335                 if (app.dynv[i]==DT_DEBUG)
1336                         app.dynv[i+1] = (size_t)&debug;
1337 #endif
1338
1339         /* The main program must be relocated LAST since it may contin
1340          * copy relocations which depend on libraries' relocations. */
1341         reloc_all(app.next);
1342         reloc_all(&app);
1343
1344         update_tls_size();
1345         if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1346                 void *initial_tls = calloc(libc.tls_size, 1);
1347                 if (!initial_tls) {
1348                         dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1349                                 argv[0], libc.tls_size);
1350                         _exit(127);
1351                 }
1352                 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1353                         a_crash();
1354                 }
1355         } else {
1356                 size_t tmp_tls_size = libc.tls_size;
1357                 pthread_t self = __pthread_self();
1358                 /* Temporarily set the tls size to the full size of
1359                  * builtin_tls so that __copy_tls will use the same layout
1360                  * as it did for before. Then check, just to be safe. */
1361                 libc.tls_size = sizeof builtin_tls;
1362                 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1363                 libc.tls_size = tmp_tls_size;
1364         }
1365         static_tls_cnt = tls_cnt;
1366
1367         if (ldso_fail) _exit(127);
1368         if (ldd_mode) _exit(0);
1369
1370         /* Switch to runtime mode: any further failures in the dynamic
1371          * linker are a reportable failure rather than a fatal startup
1372          * error. */
1373         runtime = 1;
1374
1375         debug.ver = 1;
1376         debug.bp = dl_debug_state;
1377         debug.head = head;
1378         debug.base = ldso.base;
1379         debug.state = 0;
1380         _dl_debug_state();
1381
1382         __init_libc(envp, argv[0]);
1383         atexit(do_fini);
1384         errno = 0;
1385         do_init_fini(tail);
1386
1387         CRTJMP((void *)aux[AT_ENTRY], argv-1);
1388         for(;;);
1389 }
1390
1391 void *dlopen(const char *file, int mode)
1392 {
1393         struct dso *volatile p, *orig_tail, *next;
1394         size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1395         size_t i;
1396         int cs;
1397         jmp_buf jb;
1398
1399         if (!file) return head;
1400
1401         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1402         pthread_rwlock_wrlock(&lock);
1403         __inhibit_ptc();
1404
1405         p = 0;
1406         orig_tls_cnt = tls_cnt;
1407         orig_tls_offset = tls_offset;
1408         orig_tls_align = tls_align;
1409         orig_tail = tail;
1410         noload = mode & RTLD_NOLOAD;
1411
1412         rtld_fail = &jb;
1413         if (setjmp(*rtld_fail)) {
1414                 /* Clean up anything new that was (partially) loaded */
1415                 if (p && p->deps) for (i=0; p->deps[i]; i++)
1416                         if (p->deps[i]->global < 0)
1417                                 p->deps[i]->global = 0;
1418                 for (p=orig_tail->next; p; p=next) {
1419                         next = p->next;
1420                         munmap(p->map, p->map_len);
1421                         while (p->td_index) {
1422                                 void *tmp = p->td_index->next;
1423                                 free(p->td_index);
1424                                 p->td_index = tmp;
1425                         }
1426                         if (p->rpath != p->rpath_orig)
1427                                 free(p->rpath);
1428                         free(p->deps);
1429                         free(p);
1430                 }
1431                 tls_cnt = orig_tls_cnt;
1432                 tls_offset = orig_tls_offset;
1433                 tls_align = orig_tls_align;
1434                 tail = orig_tail;
1435                 tail->next = 0;
1436                 p = 0;
1437                 goto end;
1438         } else p = load_library(file, head);
1439
1440         if (!p) {
1441                 error(noload ?
1442                         "Library %s is not already loaded" :
1443                         "Error loading shared library %s: %m",
1444                         file);
1445                 goto end;
1446         }
1447
1448         /* First load handling */
1449         if (!p->deps) {
1450                 load_deps(p);
1451                 if (p->deps) for (i=0; p->deps[i]; i++)
1452                         if (!p->deps[i]->global)
1453                                 p->deps[i]->global = -1;
1454                 if (!p->global) p->global = -1;
1455                 reloc_all(p);
1456                 if (p->deps) for (i=0; p->deps[i]; i++)
1457                         if (p->deps[i]->global < 0)
1458                                 p->deps[i]->global = 0;
1459                 if (p->global < 0) p->global = 0;
1460         }
1461
1462         if (mode & RTLD_GLOBAL) {
1463                 if (p->deps) for (i=0; p->deps[i]; i++)
1464                         p->deps[i]->global = 1;
1465                 p->global = 1;
1466         }
1467
1468         update_tls_size();
1469         _dl_debug_state();
1470         orig_tail = tail;
1471 end:
1472         __release_ptc();
1473         if (p) gencnt++;
1474         pthread_rwlock_unlock(&lock);
1475         if (p) do_init_fini(orig_tail);
1476         pthread_setcancelstate(cs, 0);
1477         return p;
1478 }
1479
1480 static int invalid_dso_handle(void *h)
1481 {
1482         struct dso *p;
1483         for (p=head; p; p=p->next) if (h==p) return 0;
1484         error("Invalid library handle %p", (void *)h);
1485         return 1;
1486 }
1487
1488 void *__tls_get_addr(size_t *);
1489
1490 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1491 {
1492         size_t i;
1493         uint32_t h = 0, gh = 0;
1494         Sym *sym;
1495         if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1496                 if (p == RTLD_DEFAULT) {
1497                         p = head;
1498                 } else if (p == RTLD_NEXT) {
1499                         for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1500                         if (!p) p=head;
1501                         p = p->next;
1502                 }
1503                 struct symdef def = find_sym(p, s, 0);
1504                 if (!def.sym) goto failed;
1505                 if ((def.sym->st_info&0xf) == STT_TLS)
1506                         return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1507                 return def.dso->base + def.sym->st_value;
1508         }
1509         if (invalid_dso_handle(p))
1510                 return 0;
1511         if (p->ghashtab) {
1512                 gh = gnu_hash(s);
1513                 sym = gnu_lookup(s, gh, p);
1514         } else {
1515                 h = sysv_hash(s);
1516                 sym = sysv_lookup(s, h, p);
1517         }
1518         if (sym && (sym->st_info&0xf) == STT_TLS)
1519                 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1520         if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1521                 return p->base + sym->st_value;
1522         if (p->deps) for (i=0; p->deps[i]; i++) {
1523                 if (p->deps[i]->ghashtab) {
1524                         if (!gh) gh = gnu_hash(s);
1525                         sym = gnu_lookup(s, gh, p->deps[i]);
1526                 } else {
1527                         if (!h) h = sysv_hash(s);
1528                         sym = sysv_lookup(s, h, p->deps[i]);
1529                 }
1530                 if (sym && (sym->st_info&0xf) == STT_TLS)
1531                         return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1532                 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1533                         return p->deps[i]->base + sym->st_value;
1534         }
1535 failed:
1536         error("Symbol not found: %s", s);
1537         return 0;
1538 }
1539
1540 int __dladdr(const void *addr, Dl_info *info)
1541 {
1542         struct dso *p;
1543         Sym *sym;
1544         uint32_t nsym;
1545         char *strings;
1546         size_t i;
1547         void *best = 0;
1548         char *bestname;
1549
1550         pthread_rwlock_rdlock(&lock);
1551         for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1552         pthread_rwlock_unlock(&lock);
1553
1554         if (!p) return 0;
1555
1556         sym = p->syms;
1557         strings = p->strings;
1558         if (p->hashtab) {
1559                 nsym = p->hashtab[1];
1560         } else {
1561                 uint32_t *buckets;
1562                 uint32_t *hashval;
1563                 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1564                 sym += p->ghashtab[1];
1565                 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1566                         if (buckets[i] > nsym)
1567                                 nsym = buckets[i];
1568                 }
1569                 if (nsym) {
1570                         nsym -= p->ghashtab[1];
1571                         hashval = buckets + p->ghashtab[0] + nsym;
1572                         do nsym++;
1573                         while (!(*hashval++ & 1));
1574                 }
1575         }
1576
1577         for (; nsym; nsym--, sym++) {
1578                 if (sym->st_value
1579                  && (1<<(sym->st_info&0xf) & OK_TYPES)
1580                  && (1<<(sym->st_info>>4) & OK_BINDS)) {
1581                         void *symaddr = p->base + sym->st_value;
1582                         if (symaddr > addr || symaddr < best)
1583                                 continue;
1584                         best = symaddr;
1585                         bestname = strings + sym->st_name;
1586                         if (addr == symaddr)
1587                                 break;
1588                 }
1589         }
1590
1591         if (!best) return 0;
1592
1593         info->dli_fname = p->name;
1594         info->dli_fbase = p->base;
1595         info->dli_sname = bestname;
1596         info->dli_saddr = best;
1597
1598         return 1;
1599 }
1600
1601 __attribute__((__visibility__("hidden")))
1602 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1603 {
1604         void *res;
1605         pthread_rwlock_rdlock(&lock);
1606         res = do_dlsym(p, s, ra);
1607         pthread_rwlock_unlock(&lock);
1608         return res;
1609 }
1610
1611 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1612 {
1613         struct dso *current;
1614         struct dl_phdr_info info;
1615         int ret = 0;
1616         for(current = head; current;) {
1617                 info.dlpi_addr      = (uintptr_t)current->base;
1618                 info.dlpi_name      = current->name;
1619                 info.dlpi_phdr      = current->phdr;
1620                 info.dlpi_phnum     = current->phnum;
1621                 info.dlpi_adds      = gencnt;
1622                 info.dlpi_subs      = 0;
1623                 info.dlpi_tls_modid = current->tls_id;
1624                 info.dlpi_tls_data  = current->tls_image;
1625
1626                 ret = (callback)(&info, sizeof (info), data);
1627
1628                 if (ret != 0) break;
1629
1630                 pthread_rwlock_rdlock(&lock);
1631                 current = current->next;
1632                 pthread_rwlock_unlock(&lock);
1633         }
1634         return ret;
1635 }
1636 #else
1637 static int invalid_dso_handle(void *h)
1638 {
1639         error("Invalid library handle %p", (void *)h);
1640         return 1;
1641 }
1642 void *dlopen(const char *file, int mode)
1643 {
1644         error("Dynamic loading not supported");
1645         return 0;
1646 }
1647 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1648 {
1649         error("Symbol not found: %s", s);
1650         return 0;
1651 }
1652 int __dladdr (const void *addr, Dl_info *info)
1653 {
1654         return 0;
1655 }
1656 #endif
1657
1658 int __dlinfo(void *dso, int req, void *res)
1659 {
1660         if (invalid_dso_handle(dso)) return -1;
1661         if (req != RTLD_DI_LINKMAP) {
1662                 error("Unsupported request %d", req);
1663                 return -1;
1664         }
1665         *(struct link_map **)res = dso;
1666         return 0;
1667 }
1668
1669 char *dlerror()
1670 {
1671         pthread_t self = __pthread_self();
1672         if (!self->dlerror_flag) return 0;
1673         self->dlerror_flag = 0;
1674         char *s = self->dlerror_buf;
1675         if (s == (void *)-1)
1676                 return "Dynamic linker failed to allocate memory for error message";
1677         else
1678                 return s;
1679 }
1680
1681 int dlclose(void *p)
1682 {
1683         return invalid_dso_handle(p);
1684 }
1685
1686 void __dl_thread_cleanup(void)
1687 {
1688         pthread_t self = __pthread_self();
1689         if (self->dlerror_buf != (void *)-1)
1690                 free(self->dlerror_buf);
1691 }
1692
1693 static void error(const char *fmt, ...)
1694 {
1695         va_list ap;
1696         va_start(ap, fmt);
1697 #ifdef SHARED
1698         if (!runtime) {
1699                 vdprintf(2, fmt, ap);
1700                 dprintf(2, "\n");
1701                 ldso_fail = 1;
1702                 va_end(ap);
1703                 return;
1704         }
1705 #endif
1706         pthread_t self = __pthread_self();
1707         if (self->dlerror_buf != (void *)-1)
1708                 free(self->dlerror_buf);
1709         size_t len = vsnprintf(0, 0, fmt, ap);
1710         va_end(ap);
1711         char *buf = malloc(len+1);
1712         if (buf) {
1713                 va_start(ap, fmt);
1714                 vsnprintf(buf, len+1, fmt, ap);
1715                 va_end(ap);
1716         } else {
1717                 buf = (void *)-1;
1718         }
1719         self->dlerror_buf = buf;
1720         self->dlerror_flag = 1;
1721 }