1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __SCCSID("@(#)nlist.c 8.1 (Berkeley) 6/4/93");
34 #include "namespace.h"
35 #include <sys/param.h>
36 #include <sys/mman.h>
37 #include <sys/stat.h>
38 #include <sys/file.h>
39 #include <arpa/inet.h>
40
41 #include <errno.h>
42 #include <a.out.h>
43 #include <stdio.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include "un-namespace.h"
47
48 #include <machine/elf.h>
49 #include <elf-hints.h>
50
51 int __fdnlist(int, struct nlist *);
52 int __elf_fdnlist(int, struct nlist *);
53 int __elf_is_okay__(Elf_Ehdr *);
54
55 int
nlist(const char * name,struct nlist * list)56 nlist(const char *name, struct nlist *list)
57 {
58 int fd, n;
59
60 fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
61 if (fd < 0)
62 return (-1);
63 n = __fdnlist(fd, list);
64 (void)_close(fd);
65 return (n);
66 }
67
68 static struct nlist_handlers {
69 int (*fn)(int fd, struct nlist *list);
70 } nlist_fn[] = {
71 { __elf_fdnlist },
72 };
73
74 int
__fdnlist(int fd,struct nlist * list)75 __fdnlist(int fd, struct nlist *list)
76 {
77 int n = -1;
78 unsigned int i;
79
80 for (i = 0; i < nitems(nlist_fn); i++) {
81 n = (nlist_fn[i].fn)(fd, list);
82 if (n != -1)
83 break;
84 }
85 return (n);
86 }
87
88 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
89
90 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
91
92 /*
93 * __elf_is_okay__ - Determine if ehdr really
94 * is ELF and valid for the target platform.
95 *
96 * WARNING: This is NOT an ELF ABI function and
97 * as such its use should be restricted.
98 */
99 int
__elf_is_okay__(Elf_Ehdr * ehdr)100 __elf_is_okay__(Elf_Ehdr *ehdr)
101 {
102 int retval = 0;
103 /*
104 * We need to check magic, class size, endianess,
105 * and version before we look at the rest of the
106 * Elf_Ehdr structure. These few elements are
107 * represented in a machine independent fashion.
108 */
109 if (IS_ELF(*ehdr) &&
110 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
111 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
112 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
113
114 /* Now check the machine dependant header */
115 if (ehdr->e_machine == ELF_TARG_MACH &&
116 ehdr->e_version == ELF_TARG_VER)
117 retval = 1;
118 }
119 return retval;
120 }
121
122 int
__elf_fdnlist(int fd,struct nlist * list)123 __elf_fdnlist(int fd, struct nlist *list)
124 {
125 struct nlist *p;
126 Elf_Off symoff = 0, symstroff = 0;
127 Elf_Size symsize = 0, symstrsize = 0;
128 Elf_Ssize cc, i;
129 int nent = -1;
130 int errsave;
131 Elf_Sym sbuf[1024];
132 Elf_Sym *s;
133 Elf_Ehdr ehdr;
134 char *strtab = NULL;
135 Elf_Shdr *shdr = NULL;
136 Elf_Size shdr_size;
137 void *base;
138 struct stat st;
139
140 /* Make sure obj is OK */
141 if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
142 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
143 !__elf_is_okay__(&ehdr) ||
144 _fstat(fd, &st) < 0)
145 return (-1);
146
147 /* calculate section header table size */
148 shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
149
150 /* Make sure it's not too big to mmap */
151 if (shdr_size > SIZE_T_MAX) {
152 errno = EFBIG;
153 return (-1);
154 }
155
156 /* mmap section header table */
157 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd,
158 (off_t)ehdr.e_shoff);
159 if (base == MAP_FAILED)
160 return (-1);
161 shdr = (Elf_Shdr *)base;
162
163 /*
164 * Find the symbol table entry and it's corresponding
165 * string table entry. Version 1.1 of the ABI states
166 * that there is only one symbol table but that this
167 * could change in the future.
168 */
169 for (i = 0; i < ehdr.e_shnum; i++) {
170 if (shdr[i].sh_type == SHT_SYMTAB) {
171 symoff = shdr[i].sh_offset;
172 symsize = shdr[i].sh_size;
173 symstroff = shdr[shdr[i].sh_link].sh_offset;
174 symstrsize = shdr[shdr[i].sh_link].sh_size;
175 break;
176 }
177 }
178
179 /* Check for files too large to mmap. */
180 if (symstrsize > SIZE_T_MAX) {
181 errno = EFBIG;
182 goto done;
183 }
184 /*
185 * Map string table into our address space. This gives us
186 * an easy way to randomly access all the strings, without
187 * making the memory allocation permanent as with malloc/free
188 * (i.e., munmap will return it to the system).
189 */
190 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd,
191 (off_t)symstroff);
192 if (base == MAP_FAILED)
193 goto done;
194 strtab = (char *)base;
195
196 /*
197 * clean out any left-over information for all valid entries.
198 * Type and value defined to be 0 if not found; historical
199 * versions cleared other and desc as well. Also figure out
200 * the largest string length so don't read any more of the
201 * string table than we have to.
202 *
203 * XXX clearing anything other than n_type and n_value violates
204 * the semantics given in the man page.
205 */
206 nent = 0;
207 for (p = list; !ISLAST(p); ++p) {
208 p->n_type = 0;
209 p->n_other = 0;
210 p->n_desc = 0;
211 p->n_value = 0;
212 ++nent;
213 }
214
215 /* Don't process any further if object is stripped. */
216 if (symoff == 0)
217 goto done;
218
219 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
220 nent = -1;
221 goto done;
222 }
223
224 while (symsize > 0 && nent > 0) {
225 cc = MIN(symsize, sizeof(sbuf));
226 if (_read(fd, sbuf, cc) != cc)
227 break;
228 symsize -= cc;
229 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
230 char *name;
231 struct nlist *p;
232
233 name = strtab + s->st_name;
234 if (name[0] == '\0')
235 continue;
236 for (p = list; !ISLAST(p); p++) {
237 if ((p->n_un.n_name[0] == '_' &&
238 strcmp(name, p->n_un.n_name+1) == 0)
239 || strcmp(name, p->n_un.n_name) == 0) {
240 elf_sym_to_nlist(p, s, shdr,
241 ehdr.e_shnum);
242 if (--nent <= 0)
243 break;
244 }
245 }
246 }
247 }
248 done:
249 errsave = errno;
250 if (strtab != NULL)
251 munmap(strtab, symstrsize);
252 if (shdr != NULL)
253 munmap(shdr, shdr_size);
254 errno = errsave;
255 return (nent);
256 }
257
258 /*
259 * Convert an Elf_Sym into an nlist structure. This fills in only the
260 * n_value and n_type members.
261 */
262 static void
elf_sym_to_nlist(struct nlist * nl,Elf_Sym * s,Elf_Shdr * shdr,int shnum)263 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
264 {
265 nl->n_value = s->st_value;
266
267 switch (s->st_shndx) {
268 case SHN_UNDEF:
269 case SHN_COMMON:
270 nl->n_type = N_UNDF;
271 break;
272 case SHN_ABS:
273 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
274 N_FN : N_ABS;
275 break;
276 default:
277 if (s->st_shndx >= shnum)
278 nl->n_type = N_UNDF;
279 else {
280 Elf_Shdr *sh = shdr + s->st_shndx;
281
282 nl->n_type = sh->sh_type == SHT_PROGBITS ?
283 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
284 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
285 }
286 break;
287 }
288
289 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
290 ELF_ST_BIND(s->st_info) == STB_WEAK)
291 nl->n_type |= N_EXT;
292 }
293