1 /* $NetBSD: search.c,v 1.27 2020/04/22 23:54:32 joerg Exp $ */
2
3 /*
4 * Copyright 1996 Matt Thomas <matt@3am-software.com>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by John Polstra.
18 * 4. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*
34 * Dynamic linker for ELF.
35 *
36 * John Polstra <jdp@polstra.com>.
37 */
38
39 #include <sys/cdefs.h>
40 #ifndef lint
41 __RCSID("$NetBSD: search.c,v 1.27 2020/04/22 23:54:32 joerg Exp $");
42 #endif /* not lint */
43
44 #include <err.h>
45 #include <errno.h>
46 #include <fcntl.h>
47 #include <stdarg.h>
48 #include <stdio.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <unistd.h>
52 #include <sys/types.h>
53 #include <sys/mman.h>
54 #include <sys/stat.h>
55 #include <dirent.h>
56
57 #include "debug.h"
58 #include "rtld.h"
59
60 /*
61 * Data declarations.
62 */
63 static Search_Path *_rtld_invalid_paths;
64
65 static Obj_Entry *_rtld_search_library_path(const char *, size_t,
66 const char *, size_t, int);
67
68 static Obj_Entry *
_rtld_search_library_path(const char * name,size_t namelen,const char * dir,size_t dirlen,int flags)69 _rtld_search_library_path(const char *name, size_t namelen,
70 const char *dir, size_t dirlen, int flags)
71 {
72 char pathname[MAXPATHLEN];
73 size_t pathnamelen;
74 Obj_Entry *obj;
75 Search_Path *sp;
76
77 pathnamelen = dirlen + 1 + namelen;
78 if (pathnamelen >= sizeof(pathname))
79 return NULL;
80
81 for (sp = _rtld_invalid_paths; sp != NULL; sp = sp->sp_next) {
82 if (sp->sp_pathlen == pathnamelen &&
83 sp->sp_path[dirlen] == '/' &&
84 !memcmp(name, sp->sp_path + dirlen + 1, namelen) &&
85 !memcmp(dir, sp->sp_path, dirlen)) {
86 return NULL;
87 }
88 }
89
90 memcpy(pathname, dir, dirlen);
91 pathname[dirlen] = '/';
92 memcpy(pathname + dirlen + 1, name, namelen);
93 pathname[pathnamelen] = '\0';
94
95 dbg((" Trying \"%s\"", pathname));
96 obj = _rtld_load_object(pathname, flags);
97 if (obj == NULL) {
98 Search_Path *path;
99
100 path = NEW(Search_Path);
101 path->sp_pathlen = pathnamelen;
102 path->sp_path = xstrdup(pathname);
103 path->sp_next = _rtld_invalid_paths;
104 _rtld_invalid_paths = path;
105 }
106 return obj;
107 }
108
109 /*
110 * Find the library with the given name, and return its full pathname.
111 * The returned string is dynamically allocated. Generates an error
112 * message and returns NULL if the library cannot be found.
113 *
114 * If the second argument is non-NULL, then it refers to an already-
115 * loaded shared object, whose library search path will be searched.
116 */
117 Obj_Entry *
_rtld_load_library(const char * name,const Obj_Entry * refobj,int flags)118 _rtld_load_library(const char *name, const Obj_Entry *refobj, int flags)
119 {
120 extern char *__progname;
121 char tmperror[512], *tmperrorp;
122 Search_Path *sp;
123 const char *pathname;
124 int namelen;
125 Obj_Entry *obj;
126
127 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
128 if (name[0] != '/' && !_rtld_trust) {
129 _rtld_error(
130 "absolute pathname required for shared object \"%s\"",
131 name);
132 return NULL;
133 }
134 pathname = name;
135 goto found;
136 }
137 dbg((" Searching for \"%s\" (%p)", name, refobj));
138
139 tmperrorp = dlerror();
140 if (tmperrorp != NULL) {
141 strlcpy(tmperror, tmperrorp, sizeof(tmperror));
142 tmperrorp = tmperror;
143 }
144
145 namelen = strlen(name);
146
147 for (sp = _rtld_paths; sp != NULL; sp = sp->sp_next)
148 if ((obj = _rtld_search_library_path(name, namelen,
149 sp->sp_path, sp->sp_pathlen, flags)) != NULL)
150 goto pathfound;
151
152 if (refobj != NULL)
153 for (sp = refobj->rpaths; sp != NULL; sp = sp->sp_next)
154 if ((obj = _rtld_search_library_path(name,
155 namelen, sp->sp_path, sp->sp_pathlen, flags)) != NULL)
156 goto pathfound;
157
158 for (sp = _rtld_default_paths; sp != NULL; sp = sp->sp_next)
159 if ((obj = _rtld_search_library_path(name, namelen,
160 sp->sp_path, sp->sp_pathlen, flags)) != NULL)
161 goto pathfound;
162
163 _rtld_error("%s: Shared object \"%s\" not found",
164 refobj ? refobj->path : __progname, name);
165 return NULL;
166
167 pathfound:
168 /*
169 * The library has been found, but it couldn't be loaded for some
170 * reason.
171 */
172 if (obj == OBJ_ERR)
173 return NULL;
174 /*
175 * Successfully found a library; restore the dlerror state as it was
176 * before _rtld_load_library() was called (any failed call to
177 * _rtld_search_library_path() will set the dlerror state, but if the
178 * library was eventually found, then the error state should not
179 * change.
180 */
181 if (tmperrorp)
182 _rtld_error("%s", tmperror);
183 else
184 (void)dlerror();
185 return obj;
186
187 found:
188 obj = _rtld_load_object(pathname, flags);
189 if (obj == OBJ_ERR)
190 return NULL;
191
192 return obj;
193 }
194
195