1 /* $NetBSD: load.c,v 1.49 2020/09/21 16:08:57 kamil 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 1.49 2020/09/21 16:08:57 kamil Exp $");
44 #endif /* not lint */
45
46 #include <sys/types.h>
47 #include <sys/param.h>
48 #include <sys/mman.h>
49 #include <sys/sysctl.h>
50 #include <sys/stat.h>
51
52 #include <err.h>
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <stdarg.h>
56 #include <stdio.h>
57 #include <stdlib.h>
58 #include <string.h>
59 #include <unistd.h>
60 #include <dirent.h>
61
62 #include "debug.h"
63 #include "rtld.h"
64
65 static bool _rtld_load_by_name(const char *, Obj_Entry *, Needed_Entry **,
66 int);
67
68 #ifdef RTLD_LOADER
69 Objlist _rtld_list_main = /* Objects loaded at program startup */
70 SIMPLEQ_HEAD_INITIALIZER(_rtld_list_main);
71 Objlist _rtld_list_global = /* Objects dlopened with RTLD_GLOBAL */
72 SIMPLEQ_HEAD_INITIALIZER(_rtld_list_global);
73
74 void
_rtld_objlist_push_head(Objlist * list,Obj_Entry * obj)75 _rtld_objlist_push_head(Objlist *list, Obj_Entry *obj)
76 {
77 Objlist_Entry *elm;
78
79 elm = NEW(Objlist_Entry);
80 elm->obj = obj;
81 SIMPLEQ_INSERT_HEAD(list, elm, link);
82 }
83
84 void
_rtld_objlist_push_tail(Objlist * list,Obj_Entry * obj)85 _rtld_objlist_push_tail(Objlist *list, Obj_Entry *obj)
86 {
87 Objlist_Entry *elm;
88
89 elm = NEW(Objlist_Entry);
90 elm->obj = obj;
91 SIMPLEQ_INSERT_TAIL(list, elm, link);
92 }
93
94 Objlist_Entry *
_rtld_objlist_find(Objlist * list,const Obj_Entry * obj)95 _rtld_objlist_find(Objlist *list, const Obj_Entry *obj)
96 {
97 Objlist_Entry *elm;
98
99 SIMPLEQ_FOREACH(elm, list, link) {
100 if (elm->obj == obj)
101 return elm;
102 }
103 return NULL;
104 }
105 #endif
106
107 /*
108 * Load a shared object into memory, if it is not already loaded.
109 *
110 * Returns a pointer to the Obj_Entry for the object. Returns NULL
111 * on failure.
112 */
113 Obj_Entry *
_rtld_load_object(const char * filepath,int flags)114 _rtld_load_object(const char *filepath, int flags)
115 {
116 Obj_Entry *obj;
117 int fd = -1;
118 struct stat sb;
119 size_t pathlen = strlen(filepath);
120
121 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next)
122 if (pathlen == obj->pathlen && !strcmp(obj->path, filepath))
123 break;
124
125 /*
126 * If we didn't find a match by pathname, open the file and check
127 * again by device and inode. This avoids false mismatches caused
128 * by multiple links or ".." in pathnames.
129 *
130 * To avoid a race, we open the file and use fstat() rather than
131 * using stat().
132 */
133 if (obj == NULL) {
134 if ((fd = open(filepath, O_RDONLY)) == -1) {
135 _rtld_error("Cannot open \"%s\"", filepath);
136 return NULL;
137 }
138 if (fstat(fd, &sb) == -1) {
139 _rtld_error("Cannot fstat \"%s\"", filepath);
140 close(fd);
141 return NULL;
142 }
143 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) {
144 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
145 close(fd);
146 break;
147 }
148 }
149 }
150
151 #ifdef RTLD_LOADER
152 if (pathlen == _rtld_objself.pathlen &&
153 strcmp(_rtld_objself.path, filepath) == 0) {
154 close(fd);
155 return &_rtld_objself;
156 }
157 #endif
158
159 if (obj == NULL) { /* First use of this object, so we must map it in */
160 obj = _rtld_map_object(filepath, fd, &sb);
161 (void)close(fd);
162 if (obj == NULL)
163 return NULL;
164 _rtld_digest_dynamic(filepath, obj);
165
166 if (flags & _RTLD_DLOPEN) {
167 if (obj->z_noopen || (flags & _RTLD_NOLOAD)) {
168 dbg(("refusing to load non-loadable \"%s\"",
169 obj->path));
170 _rtld_error("Cannot dlopen non-loadable %s",
171 obj->path);
172 munmap(obj->mapbase, obj->mapsize);
173 _rtld_obj_free(obj);
174 return OBJ_ERR;
175 }
176 }
177
178 *_rtld_objtail = obj;
179 _rtld_objtail = &obj->next;
180 _rtld_objcount++;
181 _rtld_objloads++;
182 #ifdef RTLD_LOADER
183 _rtld_linkmap_add(obj); /* for the debugger */
184 #endif
185 dbg((" %p .. %p: %s", obj->mapbase,
186 obj->mapbase + obj->mapsize - 1, obj->path));
187 if (obj->textrel)
188 dbg((" WARNING: %s has impure text", obj->path));
189 }
190
191 ++obj->refcount;
192 #ifdef RTLD_LOADER
193 if (flags & _RTLD_MAIN && !obj->mainref) {
194 obj->mainref = 1;
195 dbg(("adding %p (%s) to _rtld_list_main", obj, obj->path));
196 _rtld_objlist_push_tail(&_rtld_list_main, obj);
197 }
198 if (flags & _RTLD_GLOBAL && !obj->globalref) {
199 obj->globalref = 1;
200 dbg(("adding %p (%s) to _rtld_list_global", obj, obj->path));
201 _rtld_objlist_push_tail(&_rtld_list_global, obj);
202 }
203 #endif
204 return obj;
205 }
206
207 static bool
_rtld_load_by_name(const char * name,Obj_Entry * obj,Needed_Entry ** needed,int flags)208 _rtld_load_by_name(const char *name, Obj_Entry *obj, Needed_Entry **needed,
209 int flags)
210 {
211 Library_Xform *x = _rtld_xforms;
212 Obj_Entry *o;
213 size_t j;
214 ssize_t i;
215 bool got = false;
216 union {
217 int i;
218 u_quad_t q;
219 char s[16];
220 } val;
221
222 dbg(("load by name %s %p", name, x));
223 for (o = _rtld_objlist->next; o != NULL; o = o->next)
224 if (_rtld_object_match_name(o, name)) {
225 ++o->refcount;
226 (*needed)->obj = o;
227 return true;
228 }
229
230 for (; x; x = x->next) {
231 if (strcmp(x->name, name) != 0)
232 continue;
233
234 j = sizeof(val);
235 if ((i = _rtld_sysctl(x->ctlname, &val, &j)) == -1) {
236 xwarnx(_PATH_LD_HINTS ": invalid/unknown sysctl for %s (%d)",
237 name, errno);
238 break;
239 }
240
241 switch (i) {
242 case CTLTYPE_QUAD:
243 xsnprintf(val.s, sizeof(val.s), "%" PRIu64, val.q);
244 break;
245 case CTLTYPE_INT:
246 xsnprintf(val.s, sizeof(val.s), "%d", val.i);
247 break;
248 case CTLTYPE_STRING:
249 break;
250 default:
251 xwarnx("unsupported sysctl type %d", (int)i);
252 break;
253 }
254
255 dbg(("sysctl returns %s", val.s));
256
257 for (i = 0; i < RTLD_MAX_ENTRY && x->entry[i].value != NULL;
258 i++) {
259 dbg(("entry %ld", (unsigned long)i));
260 if (strcmp(x->entry[i].value, val.s) == 0)
261 break;
262 }
263
264 if (i == RTLD_MAX_ENTRY) {
265 xwarnx("sysctl value %s not found for lib%s",
266 val.s, name);
267 break;
268 }
269
270 for (j = 0; j < RTLD_MAX_LIBRARY &&
271 x->entry[i].library[j] != NULL; j++) {
272 o = _rtld_load_library(x->entry[i].library[j], obj,
273 flags);
274 if (o == NULL) {
275 xwarnx("could not load %s for %s",
276 x->entry[i].library[j], name);
277 continue;
278 }
279 got = true;
280 if (j == 0)
281 (*needed)->obj = o;
282 else {
283 /* make a new one and put it in the chain */
284 Needed_Entry *ne = xmalloc(sizeof(*ne));
285 ne->name = (*needed)->name;
286 ne->obj = o;
287 ne->next = (*needed)->next;
288 (*needed)->next = ne;
289 *needed = ne;
290 }
291
292 }
293
294 }
295
296 if (got)
297 return true;
298
299 return ((*needed)->obj = _rtld_load_library(name, obj, flags)) != NULL;
300 }
301
302
303 /*
304 * Given a shared object, traverse its list of needed objects, and load
305 * each of them. Returns 0 on success. Generates an error message and
306 * returns -1 on failure.
307 */
308 int
_rtld_load_needed_objects(Obj_Entry * first,int flags)309 _rtld_load_needed_objects(Obj_Entry *first, int flags)
310 {
311 Obj_Entry *obj;
312 int status = 0;
313
314 for (obj = first; obj != NULL; obj = obj->next) {
315 Needed_Entry *needed;
316
317 for (needed = obj->needed; needed != NULL;
318 needed = needed->next) {
319 const char *name = obj->strtab + needed->name;
320 #ifdef RTLD_LOADER
321 Obj_Entry *nobj;
322 #endif
323 if (!_rtld_load_by_name(name, obj, &needed,
324 flags & ~_RTLD_NOLOAD))
325 status = -1; /* FIXME - cleanup */
326 #ifdef RTLD_LOADER
327 if (status == -1)
328 return status;
329
330 if (flags & _RTLD_MAIN)
331 continue;
332
333 nobj = needed->obj;
334 if (nobj->z_nodelete && !obj->ref_nodel) {
335 dbg(("obj %s nodelete", nobj->path));
336 _rtld_ref_dag(nobj);
337 nobj->ref_nodel = true;
338 }
339 #endif
340 }
341 }
342
343 return status;
344 }
345
346 #ifdef RTLD_LOADER
347 int
_rtld_preload(const char * preload_path)348 _rtld_preload(const char *preload_path)
349 {
350 const char *path;
351 char *cp, *buf;
352 int status = 0;
353
354 if (preload_path != NULL && *preload_path != '\0') {
355 cp = buf = xstrdup(preload_path);
356 while ((path = strsep(&cp, " :")) != NULL && status == 0) {
357 if (!_rtld_load_object(path, _RTLD_MAIN))
358 status = -1;
359 else
360 dbg((" preloaded \"%s\"", path));
361 }
362 xfree(buf);
363 }
364
365 return status;
366 }
367 #endif
368