1 /* $OpenBSD: sod.c,v 1.37 2022/11/05 18:48:31 deraadt Exp $ */
2
3 /*
4 * Copyright (c) 1993 Paul Kranenburg
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 Paul Kranenburg.
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 #include <sys/types.h>
35 #include <sys/mman.h>
36 #include <sys/stat.h>
37
38 #include <limits.h>
39 #include <fcntl.h>
40 #include <link.h> /* for _PATH_LD_HINTS */
41 #include <string.h>
42
43 #include "syscall.h"
44 #include "path.h"
45 #include "util.h"
46 #include "sod.h"
47
48 int _dl_hinthash(char *cp, int vmajor, int vminor);
49 void _dl_maphints(void);
50
51 /*
52 * Populate sod struct for dlopen's call to map_object
53 */
54 void
_dl_build_sod(const char * name,struct sod * sodp)55 _dl_build_sod(const char *name, struct sod *sodp)
56 {
57 unsigned int tuplet;
58 int major, minor;
59 char *realname, *tok, *etok, *cp;
60
61 /* default is an absolute or relative path */
62 sodp->sod_name = (long)_dl_strdup(name); /* strtok is destructive */
63 if (sodp->sod_name == 0)
64 _dl_oom();
65 sodp->sod_library = 0;
66 sodp->sod_major = sodp->sod_minor = 0;
67
68 /* does it look like /^lib/ ? */
69 if (_dl_strncmp((char *)sodp->sod_name, "lib", 3) != 0)
70 goto backout;
71
72 /* is this a filename? */
73 if (_dl_strchr((char *)sodp->sod_name, '/'))
74 goto backout;
75
76 /* skip over 'lib' */
77 cp = (char *)sodp->sod_name + 3;
78
79 realname = cp;
80
81 /* dot guardian */
82 if ((_dl_strchr(cp, '.') == NULL) || (*(cp+_dl_strlen(cp)-1) == '.'))
83 goto backout;
84
85 cp = _dl_strstr(cp, ".so");
86 if (cp == NULL)
87 goto backout;
88
89 /* default */
90 major = minor = -1;
91
92 /* loop through name - parse skipping name */
93 for (tuplet = 0; (tok = _dl_strsep(&cp, ".")) != NULL; tuplet++) {
94 switch (tuplet) {
95 case 0:
96 /* empty tok, we already skipped to "\.so.*" */
97 break;
98 case 1:
99 /* 'so' extension */
100 break;
101 case 2:
102 /* major version extension */
103 major = _dl_strtol(tok, &etok, 10);
104 if (*tok == '\0' || *etok != '\0')
105 goto backout;
106 break;
107 case 3:
108 /* minor version extension */
109 minor = _dl_strtol(tok, &etok, 10);
110 if (*tok == '\0' || *etok != '\0')
111 goto backout;
112 break;
113 /* if we get here, it must be weird */
114 default:
115 goto backout;
116 }
117 }
118 if (realname == NULL)
119 goto backout;
120 cp = (char *)sodp->sod_name;
121 sodp->sod_name = (long)_dl_strdup(realname);
122 if (sodp->sod_name == 0)
123 _dl_oom();
124 _dl_free(cp);
125 sodp->sod_library = 1;
126 sodp->sod_major = major;
127 sodp->sod_minor = minor;
128 return;
129
130 backout:
131 _dl_free((char *)sodp->sod_name);
132 sodp->sod_name = (long)_dl_strdup(name);
133 if (sodp->sod_name == 0)
134 _dl_oom();
135 }
136
137 void
_dl_set_sod(const char * path,struct sod * sod)138 _dl_set_sod(const char *path, struct sod *sod)
139 {
140 char *fname = _dl_strrchr(path, '/');
141
142 if (fname != NULL)
143 _dl_build_sod(++fname, sod);
144 else
145 _dl_build_sod(path, sod);
146 }
147
148 static struct hints_header *hheader = NULL;
149 static struct hints_bucket *hbuckets;
150 static char *hstrtab;
151 char **_dl_hint_search_path = NULL;
152
153 #define HINTS_VALID (hheader != NULL && hheader != (struct hints_header *)-1)
154
155 void
_dl_maphints(void)156 _dl_maphints(void)
157 {
158 struct stat sb;
159 caddr_t addr = MAP_FAILED;
160 long hsize = 0;
161 int hfd;
162
163 if ((hfd = _dl_open(_PATH_LD_HINTS, O_RDONLY | O_CLOEXEC)) < 0) {
164 hfd = -1;
165 goto bad_hints;
166 }
167
168 if (_dl_fstat(hfd, &sb) != 0 || !S_ISREG(sb.st_mode) ||
169 sb.st_size < sizeof(struct hints_header) || sb.st_size > LONG_MAX)
170 goto bad_hints;
171
172 hsize = (long)sb.st_size;
173 addr = (void *)_dl_mmap(0, hsize, PROT_READ, MAP_PRIVATE, hfd, 0);
174 if (_dl_mmap_error(addr))
175 goto bad_hints;
176
177 hheader = (struct hints_header *)addr;
178 if (HH_BADMAG(*hheader) || hheader->hh_ehints > hsize)
179 goto bad_hints;
180
181 if (hheader->hh_version != LD_HINTS_VERSION_2)
182 goto bad_hints;
183
184 hbuckets = (struct hints_bucket *)(addr + hheader->hh_hashtab);
185 hstrtab = (char *)(addr + hheader->hh_strtab);
186 if (hheader->hh_version >= LD_HINTS_VERSION_2)
187 _dl_hint_search_path = _dl_split_path(hstrtab + hheader->hh_dirlist);
188
189 _dl_mimmutable(addr, hsize);
190
191 /* close the file descriptor, leaving the hints mapped */
192 _dl_close(hfd);
193
194 return;
195
196 bad_hints:
197 if (!_dl_mmap_error(addr))
198 _dl_munmap(addr, hsize);
199 if (hfd != -1)
200 _dl_close(hfd);
201 hheader = (struct hints_header *)-1;
202 }
203
204 char *
_dl_findhint(char * name,int major,int minor,char * preferred_path)205 _dl_findhint(char *name, int major, int minor, char *preferred_path)
206 {
207 struct hints_bucket *bp;
208
209 /*
210 * If not mapped, and we have not tried before, try to map the
211 * hints, if previous attempts failed hheader is -1 and we
212 * do not wish to retry it.
213 */
214 if (hheader == NULL)
215 _dl_maphints();
216
217 /* if it failed to map, return failure */
218 if (!(HINTS_VALID))
219 return NULL;
220
221 if (hheader->hh_nbucket == 0)
222 return NULL;
223
224 bp = hbuckets + (_dl_hinthash(name, major, minor) % hheader->hh_nbucket);
225
226 while (1) {
227 /* Sanity check */
228 if (bp->hi_namex >= hheader->hh_strtab_sz)
229 _dl_die("bad name index: %#x", bp->hi_namex);
230 if (bp->hi_pathx >= hheader->hh_strtab_sz)
231 _dl_die("bad path index: %#x", bp->hi_pathx);
232
233 if (_dl_strcmp(name, hstrtab + bp->hi_namex) == 0) {
234 /* It's `name', check version numbers */
235 if (bp->hi_major == major &&
236 (bp->hi_ndewey < 2 || bp->hi_minor >= minor)) {
237 if (preferred_path == NULL) {
238 return hstrtab + bp->hi_pathx;
239 } else {
240 char *path = hstrtab + bp->hi_pathx;
241 char *edir = _dl_strrchr(path, '/');
242
243 if ((_dl_strncmp(preferred_path, path,
244 (edir - path)) == 0) &&
245 (preferred_path[edir - path] == '\0'))
246 return path;
247 }
248 }
249 }
250
251 if (bp->hi_next == -1)
252 break;
253
254 /* Move on to next in bucket */
255 bp = &hbuckets[bp->hi_next];
256 }
257
258 /* No hints available for name */
259 return NULL;
260 }
261
262 int
_dl_hinthash(char * cp,int vmajor,int vminor)263 _dl_hinthash(char *cp, int vmajor, int vminor)
264 {
265 int k = 0;
266
267 while (*cp)
268 k = (((k << 1) + (k >> 14)) ^ (*cp++)) & 0x3fff;
269
270 k = (((k << 1) + (k >> 14)) ^ (vmajor*257)) & 0x3fff;
271
272 return k;
273 }
274