libexec/ld.elf_so/load.c

   1 /*      $NetBSD: load.c,v 1.47 2013/11/27 18:01:33 christos 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 1.47 2013/11/27 18:01:33 christos 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 #include "debug.h"
  61 #include "rtld.h"
  62
  63 static bool _rtld_load_by_name(const char *, Obj_Entry *, Needed_Entry **,
  64     int);
  65
  66 #ifdef RTLD_LOADER
  67 Objlist _rtld_list_main =       /* Objects loaded at program startup */
  68   SIMPLEQ_HEAD_INITIALIZER(_rtld_list_main);
  69 Objlist _rtld_list_global =     /* Objects dlopened with RTLD_GLOBAL */
  70   SIMPLEQ_HEAD_INITIALIZER(_rtld_list_global);
  71
  72 void
  73 _rtld_objlist_push_head(Objlist *list, Obj_Entry *obj)
  74 {
  75         Objlist_Entry *elm;
  76
  77         elm = NEW(Objlist_Entry);
  78         elm->obj = obj;
  79         SIMPLEQ_INSERT_HEAD(list, elm, link);
  80 }
  81
  82 void
  83 _rtld_objlist_push_tail(Objlist *list, Obj_Entry *obj)
  84 {
  85         Objlist_Entry *elm;
  86
  87         elm = NEW(Objlist_Entry);
  88         elm->obj = obj;
  89         SIMPLEQ_INSERT_TAIL(list, elm, link);
  90 }
  91
  92 Objlist_Entry *
  93 _rtld_objlist_find(Objlist *list, const Obj_Entry *obj)
  94 {
  95         Objlist_Entry *elm;
  96
  97         SIMPLEQ_FOREACH(elm, list, link) {
  98                 if (elm->obj == obj)
  99                         return elm;
 100         }
 101         return NULL;
 102 }
 103 #endif
 104
 105 /*
 106  * Load a shared object into memory, if it is not already loaded.
 107  *
 108  * Returns a pointer to the Obj_Entry for the object.  Returns NULL
 109  * on failure.
 110  */
 111 Obj_Entry *
 112 _rtld_load_object(const char *filepath, int flags)
 113 {
 114         Obj_Entry *obj;
 115         int fd = -1;
 116         struct stat sb;
 117         size_t pathlen = strlen(filepath);
 118
 119         for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next)
 120                 if (pathlen == obj->pathlen && !strcmp(obj->path, filepath))
 121                         break;
 122
 123         /*
 124          * If we didn't find a match by pathname, open the file and check
 125          * again by device and inode.  This avoids false mismatches caused
 126          * by multiple links or ".." in pathnames.
 127          *
 128          * To avoid a race, we open the file and use fstat() rather than
 129          * using stat().
 130          */
 131         if (obj == NULL) {
 132                 if ((fd = open(filepath, O_RDONLY)) == -1) {
 133                         _rtld_error("Cannot open \"%s\"", filepath);
 134                         return NULL;
 135                 }
 136                 if (fstat(fd, &sb) == -1) {
 137                         _rtld_error("Cannot fstat \"%s\"", filepath);
 138                         close(fd);
 139                         return NULL;
 140                 }
 141                 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) {
 142                         if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
 143                                 close(fd);
 144                                 break;
 145                         }
 146                 }
 147         }
 148
 149 #ifdef RTLD_LOADER
 150         if (pathlen == _rtld_objself.pathlen &&
 151             strcmp(_rtld_objself.path, filepath) == 0) {
 152                 close(fd);
 153                 return &_rtld_objself;
 154         }
 155 #endif
 156
 157         if (obj == NULL) { /* First use of this object, so we must map it in */
 158                 obj = _rtld_map_object(filepath, fd, &sb);
 159                 (void)close(fd);
 160                 if (obj == NULL)
 161                         return NULL;
 162                 _rtld_digest_dynamic(filepath, obj);
 163
 164                 if (flags & _RTLD_DLOPEN) {
 165                         if (obj->z_noopen || (flags & _RTLD_NOLOAD)) {
 166                                 dbg(("refusing to load non-loadable \"%s\"",
 167                                     obj->path));
 168                                 _rtld_error("Cannot dlopen non-loadable %s",
 169                                     obj->path);
 170                                 munmap(obj->mapbase, obj->mapsize);
 171                                 _rtld_obj_free(obj);
 172                                 return OBJ_ERR;
 173                         }
 174                 }
 175
 176                 *_rtld_objtail = obj;
 177                 _rtld_objtail = &obj->next;
 178                 _rtld_objcount++;
 179                 _rtld_objloads++;
 180 #ifdef RTLD_LOADER
 181                 _rtld_linkmap_add(obj); /* for GDB */
 182 #endif
 183                 dbg(("  %p .. %p: %s", obj->mapbase,
 184                     obj->mapbase + obj->mapsize - 1, obj->path));
 185                 if (obj->textrel)
 186                         dbg(("  WARNING: %s has impure text", obj->path));
 187         }
 188
 189         ++obj->refcount;
 190 #ifdef RTLD_LOADER
 191         if (flags & _RTLD_MAIN && !obj->mainref) {
 192                 obj->mainref = 1;
 193                 dbg(("adding %p (%s) to _rtld_list_main", obj, obj->path));
 194                 _rtld_objlist_push_tail(&_rtld_list_main, obj);
 195         }
 196         if (flags & _RTLD_GLOBAL && !obj->globalref) {
 197                 obj->globalref = 1;
 198                 dbg(("adding %p (%s) to _rtld_list_global", obj, obj->path));
 199                 _rtld_objlist_push_tail(&_rtld_list_global, obj);
 200         }
 201 #endif
 202         return obj;
 203 }
 204
 205 static bool
 206 _rtld_load_by_name(const char *name, Obj_Entry *obj, Needed_Entry **needed,
 207     int flags)
 208 {
 209         Library_Xform *x = _rtld_xforms;
 210         Obj_Entry *o;
 211         size_t j;
 212         ssize_t i;
 213         bool got = false;
 214         union {
 215                 int i;
 216                 u_quad_t q;
 217                 char s[16];
 218         } val;
 219
 220         dbg(("load by name %s %p", name, x));
 221         for (o = _rtld_objlist->next; o != NULL; o = o->next)
 222                 if (_rtld_object_match_name(o, name)) {
 223                         ++o->refcount;
 224                         (*needed)->obj = o;
 225                         return true;
 226                 }
 227
 228         for (; x; x = x->next) {
 229                 if (strcmp(x->name, name) != 0)
 230                         continue;
 231
 232                 j = sizeof(val);
 233                 if ((i = _rtld_sysctl(x->ctlname, &val, &j)) == -1) {
 234                         xwarnx(_PATH_LD_HINTS ": invalid/unknown sysctl for %s (%d)",
 235                             name, errno);
 236                         break;
 237                 }
 238
 239                 switch (i) {
 240                 case CTLTYPE_QUAD:
 241                         xsnprintf(val.s, sizeof(val.s), "%" PRIu64, val.q);
 242                         break;
 243                 case CTLTYPE_INT:
 244                         xsnprintf(val.s, sizeof(val.s), "%d", val.i);
 245                         break;
 246                 case CTLTYPE_STRING:
 247                         break;
 248                 default:
 249                         xwarnx("unsupported sysctl type %d", (int)i);
 250                         break;
 251                 }
 252
 253                 dbg(("sysctl returns %s", val.s));
 254
 255                 for (i = 0; i < RTLD_MAX_ENTRY && x->entry[i].value != NULL;
 256                     i++) {
 257                         dbg(("entry %ld", (unsigned long)i));
 258                         if (strcmp(x->entry[i].value, val.s) == 0)
 259                                 break;
 260                 }
 261
 262                 if (i == RTLD_MAX_ENTRY) {
 263                         xwarnx("sysctl value %s not found for lib%s",
 264                             val.s, name);
 265                         break;
 266                 }
 267
 268                 for (j = 0; j < RTLD_MAX_LIBRARY &&
 269                     x->entry[i].library[j] != NULL; j++) {
 270                         o = _rtld_load_library(x->entry[i].library[j], obj,
 271                             flags);
 272                         if (o == NULL) {
 273                                 xwarnx("could not load %s for %s",
 274                                     x->entry[i].library[j], name);
 275                                 continue;
 276                         }
 277                         got = true;
 278                         if (j == 0)
 279                                 (*needed)->obj = o;
 280                         else {
 281                                 /* make a new one and put it in the chain */
 282                                 Needed_Entry *ne = xmalloc(sizeof(*ne));
 283                                 ne->name = (*needed)->name;
 284                                 ne->obj = o;
 285                                 ne->next = (*needed)->next;
 286                                 (*needed)->next = ne;
 287                                 *needed = ne;
 288                         }
 289
 290                 }
 291
 292         }
 293
 294         if (got)
 295                 return true;
 296
 297         return ((*needed)->obj = _rtld_load_library(name, obj, flags)) != NULL;
 298 }
 299
 300
 301 /*
 302  * Given a shared object, traverse its list of needed objects, and load
 303  * each of them.  Returns 0 on success.  Generates an error message and
 304  * returns -1 on failure.
 305  */
 306 int
 307 _rtld_load_needed_objects(Obj_Entry *first, int flags)
 308 {
 309         Obj_Entry *obj;
 310         int status = 0;
 311
 312         for (obj = first; obj != NULL; obj = obj->next) {
 313                 Needed_Entry *needed;
 314
 315                 for (needed = obj->needed; needed != NULL;
 316                     needed = needed->next) {
 317                         const char *name = obj->strtab + needed->name;
 318 #ifdef RTLD_LOADER
 319                         Obj_Entry *nobj;
 320 #endif
 321                         if (!_rtld_load_by_name(name, obj, &needed,
 322                             flags & ~_RTLD_NOLOAD))
 323                                 status = -1;    /* FIXME - cleanup */
 324 #ifdef RTLD_LOADER
 325                         if (status == -1)
 326                                 return status;
 327
 328                         if (flags & _RTLD_MAIN)
 329                                 continue;
 330
 331                         nobj = needed->obj;
 332                         if (nobj->z_nodelete && !obj->ref_nodel) {
 333                                 dbg(("obj %s nodelete", nobj->path));
 334                                 _rtld_ref_dag(nobj);
 335                                 nobj->ref_nodel = true;
 336                         }
 337 #endif
 338                 }
 339         }
 340
 341         return status;
 342 }
 343
 344 #ifdef RTLD_LOADER
 345 int
 346 _rtld_preload(const char *preload_path)
 347 {
 348         const char *path;
 349         char *cp, *buf;
 350         int status = 0;
 351
 352         if (preload_path != NULL && *preload_path != '\0') {
 353                 cp = buf = xstrdup(preload_path);
 354                 while ((path = strsep(&cp, " :")) != NULL && status == 0) {
 355                         if (!_rtld_load_object(path, _RTLD_MAIN))
 356                                 status = -1;
 357                         else
 358                                 dbg((" preloaded \"%s\"", path));
 359                 }
 360                 xfree(buf);
 361         }
 362
 363         return status;
 364 }
 365 #endif