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