libexec/ld.elf_so/load.c

   1 /*      $NetBSD: load.c,v 1.42 2010/12/24 12:41:43 skrll Exp $   */
   2
   3 /*
   4  * Copyright 1996 John D. Polstra.
   5  * Copyright 1996 Matt Thomas <matt@3am-software.com>
   6  * Copyright 2002 Charles M. Hannum <root@ihack.net>
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by John Polstra.
  20  * 4. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * Dynamic linker for ELF.
  37  *
  38  * John Polstra <jdp@polstra.com>.
  39  */
  40
  41 #include <sys/cdefs.h>
  42 #ifndef lint
  43 __RCSID("$NetBSD: load.c,v 1.42 2010/12/24 12:41:43 skrll Exp $");
  44 #endif /* not lint */
  45
  46 #include <err.h>
  47 #include <errno.h>
  48 #include <fcntl.h>
  49 #include <stdarg.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <unistd.h>
  54 #include <sys/types.h>
  55 #include <sys/param.h>
  56 #include <sys/mman.h>
  57 #include <sys/sysctl.h>
  58 #include <dirent.h>
  59
  60 #ifdef __minix
  61 #define munmap minix_munmap
  62 #endif
  63
  64 #include "debug.h"
  65 #include "rtld.h"
  66
  67 static bool _rtld_load_by_name(const char *, Obj_Entry *, Needed_Entry **,
  68     int);
  69
  70 #ifdef RTLD_LOADER
  71 Objlist _rtld_list_main =       /* Objects loaded at program startup */
  72   SIMPLEQ_HEAD_INITIALIZER(_rtld_list_main);
  73 Objlist _rtld_list_global =     /* Objects dlopened with RTLD_GLOBAL */
  74   SIMPLEQ_HEAD_INITIALIZER(_rtld_list_global);
  75
  76 void
  77 _rtld_objlist_push_head(Objlist *list, Obj_Entry *obj)
  78 {
  79         Objlist_Entry *elm;
  80
  81         elm = NEW(Objlist_Entry);
  82         elm->obj = obj;
  83         SIMPLEQ_INSERT_HEAD(list, elm, link);
  84 }
  85
  86 void
  87 _rtld_objlist_push_tail(Objlist *list, Obj_Entry *obj)
  88 {
  89         Objlist_Entry *elm;
  90
  91         elm = NEW(Objlist_Entry);
  92         elm->obj = obj;
  93         SIMPLEQ_INSERT_TAIL(list, elm, link);
  94 }
  95
  96 Objlist_Entry *
  97 _rtld_objlist_find(Objlist *list, const Obj_Entry *obj)
  98 {
  99         Objlist_Entry *elm;
 100
 101         SIMPLEQ_FOREACH(elm, list, link) {
 102                 if (elm->obj == obj)
 103                         return elm;
 104         }
 105         return NULL;
 106 }
 107 #endif
 108
 109 /*
 110  * Load a shared object into memory, if it is not already loaded.
 111  *
 112  * Returns a pointer to the Obj_Entry for the object.  Returns NULL
 113  * on failure.
 114  */
 115 Obj_Entry *
 116 _rtld_load_object(const char *filepath, int flags)
 117 {
 118         Obj_Entry *obj;
 119         int fd = -1;
 120         struct stat sb;
 121         size_t pathlen = strlen(filepath);
 122
 123         for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next)
 124                 if (pathlen == obj->pathlen && !strcmp(obj->path, filepath))
 125                         break;
 126
 127         /*
 128          * If we didn't find a match by pathname, open the file and check
 129          * again by device and inode.  This avoids false mismatches caused
 130          * by multiple links or ".." in pathnames.
 131          *
 132          * To avoid a race, we open the file and use fstat() rather than
 133          * using stat().
 134          */
 135         if (obj == NULL) {
 136                 if ((fd = open(filepath, O_RDONLY)) == -1) {
 137                         _rtld_error("Cannot open \"%s\"", filepath);
 138                         return NULL;
 139                 }
 140                 if (fstat(fd, &sb) == -1) {
 141                         _rtld_error("Cannot fstat \"%s\"", filepath);
 142                         close(fd);
 143                         return NULL;
 144                 }
 145                 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) {
 146                         if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
 147                                 close(fd);
 148                                 break;
 149                         }
 150                 }
 151         }
 152
 153         if (obj == NULL) { /* First use of this object, so we must map it in */
 154                 obj = _rtld_map_object(filepath, fd, &sb);
 155                 (void)close(fd);
 156                 if (obj == NULL)
 157                         return NULL;
 158                 _rtld_digest_dynamic(filepath, obj);
 159
 160                 if (flags & _RTLD_DLOPEN) {
 161                         if (obj->z_noopen || (flags & _RTLD_NOLOAD)) {
 162                                 dbg(("refusing to load non-loadable \"%s\"",
 163                                     obj->path));
 164                                 _rtld_error("Cannot dlopen non-loadable %s",
 165                                     obj->path);
 166                                 munmap(obj->mapbase, obj->mapsize);
 167                                 _rtld_obj_free(obj);
 168                                 return OBJ_ERR;
 169                         }
 170                 }
 171
 172                 *_rtld_objtail = obj;
 173                 _rtld_objtail = &obj->next;
 174                 _rtld_objcount++;
 175                 _rtld_objloads++;
 176 #ifdef RTLD_LOADER
 177                 _rtld_linkmap_add(obj); /* for GDB */
 178 #endif
 179                 dbg(("  %p .. %p: %s", obj->mapbase,
 180                     obj->mapbase + obj->mapsize - 1, obj->path));
 181                 if (obj->textrel)
 182                         dbg(("  WARNING: %s has impure text", obj->path));
 183         }
 184
 185         ++obj->refcount;
 186 #ifdef RTLD_LOADER
 187         if (flags & _RTLD_MAIN && !obj->mainref) {
 188                 obj->mainref = 1;
 189                 dbg(("adding %p (%s) to _rtld_list_main", obj, obj->path));
 190                 _rtld_objlist_push_tail(&_rtld_list_main, obj);
 191         }
 192         if (flags & _RTLD_GLOBAL && !obj->globalref) {
 193                 obj->globalref = 1;
 194                 dbg(("adding %p (%s) to _rtld_list_global", obj, obj->path));
 195                 _rtld_objlist_push_tail(&_rtld_list_global, obj);
 196         }
 197 #endif
 198         return obj;
 199 }
 200
 201 static bool
 202 _rtld_load_by_name(const char *name, Obj_Entry *obj, Needed_Entry **needed,
 203     int flags)
 204 {
 205         Library_Xform *x = _rtld_xforms;
 206         Obj_Entry *o = NULL;
 207         size_t j;
 208         ssize_t i;
 209         bool got = false;
 210         union {
 211                 int i;
 212                 u_quad_t q;
 213                 char s[16];
 214         } val;
 215
 216         dbg(("load by name %s %p", name, x));
 217         for (; x; x = x->next) {
 218 #ifdef __minix
 219                 continue;
 220 #else
 221                 if (strcmp(x->name, name) != 0)
 222                         continue;
 223
 224                 j = sizeof(val);
 225                 if ((i = _rtld_sysctl(x->ctlname, &val, &j)) == -1) {
 226                         xwarnx(_PATH_LD_HINTS ": invalid/unknown sysctl for %s (%d)",
 227                             name, errno);
 228                         break;
 229                 }
 230
 231                 switch (i) {
 232                 case CTLTYPE_QUAD:
 233                         xsnprintf(val.s, sizeof(val.s), "%" PRIu64, val.q);
 234                         break;
 235                 case CTLTYPE_INT:
 236                         xsnprintf(val.s, sizeof(val.s), "%d", val.i);
 237                         break;
 238                 case CTLTYPE_STRING:
 239                         break;
 240                 default:
 241                         xwarnx("unsupported sysctl type %d", (int)i);
 242                         break;
 243                 }
 244
 245                 dbg(("sysctl returns %s", val.s));
 246
 247                 for (i = 0; i < RTLD_MAX_ENTRY && x->entry[i].value != NULL;
 248                     i++) {
 249                         dbg(("entry %ld", (unsigned long)i));
 250                         if (strcmp(x->entry[i].value, val.s) == 0)
 251                                 break;
 252                 }
 253
 254                 if (i == RTLD_MAX_ENTRY) {
 255                         xwarnx("sysctl value %s not found for lib%s",
 256                             val.s, name);
 257                         break;
 258                 }
 259
 260                 for (j = 0; j < RTLD_MAX_LIBRARY &&
 261                     x->entry[i].library[j] != NULL; j++) {
 262                         o = _rtld_load_library(x->entry[i].library[j], obj,
 263                             flags);
 264                         if (o == NULL) {
 265                                 xwarnx("could not load %s for %s",
 266                                     x->entry[i].library[j], name);
 267                                 continue;
 268                         }
 269                         got = true;
 270                         if (j == 0)
 271                                 (*needed)->obj = o;
 272                         else {
 273                                 /* make a new one and put it in the chain */
 274                                 Needed_Entry *ne = xmalloc(sizeof(*ne));
 275                                 ne->name = (*needed)->name;
 276                                 ne->obj = o;
 277                                 ne->next = (*needed)->next;
 278                                 (*needed)->next = ne;
 279                                 *needed = ne;
 280                         }
 281
 282                 }
 283
 284 #endif
 285         }
 286
 287         if (got)
 288                 return true;
 289
 290         return ((*needed)->obj = _rtld_load_library(name, obj, flags)) != NULL;
 291 }
 292
 293
 294 /*
 295  * Given a shared object, traverse its list of needed objects, and load
 296  * each of them.  Returns 0 on success.  Generates an error message and
 297  * returns -1 on failure.
 298  */
 299 int
 300 _rtld_load_needed_objects(Obj_Entry *first, int flags)
 301 {
 302         Obj_Entry *obj;
 303         int status = 0;
 304
 305         for (obj = first; obj != NULL; obj = obj->next) {
 306                 Needed_Entry *needed;
 307
 308                 for (needed = obj->needed; needed != NULL;
 309                     needed = needed->next) {
 310                         const char *name = obj->strtab + needed->name;
 311 #ifdef RTLD_LOADER
 312                         Obj_Entry *nobj;
 313 #endif
 314                         if (!_rtld_load_by_name(name, obj, &needed,
 315                             flags & ~_RTLD_NOLOAD))
 316                                 status = -1;    /* FIXME - cleanup */
 317 #ifdef RTLD_LOADER
 318                         if (status == -1)
 319                                 return status;
 320
 321                         if (flags & _RTLD_MAIN)
 322                                 continue;
 323
 324                         nobj = needed->obj;
 325                         if (nobj->z_nodelete && !obj->ref_nodel) {
 326                                 dbg(("obj %s nodelete", nobj->path));
 327                                 _rtld_ref_dag(nobj);
 328                                 nobj->ref_nodel = true;
 329                         }
 330 #endif
 331                 }
 332         }
 333
 334         return status;
 335 }
 336
 337 #ifdef RTLD_LOADER
 338 int
 339 _rtld_preload(const char *preload_path)
 340 {
 341         const char *path;
 342         char *cp, *buf;
 343         int status = 0;
 344
 345         if (preload_path != NULL && *preload_path != '\0') {
 346                 cp = buf = xstrdup(preload_path);
 347                 while ((path = strsep(&cp, " :")) != NULL && status == 0) {
 348                         if (!_rtld_load_object(path, _RTLD_MAIN))
 349                                 status = -1;
 350                         else
 351                                 dbg((" preloaded \"%s\"", path));
 352                 }
 353                 xfree(buf);
 354         }
 355
 356         return status;
 357 }
 358 #endif