1 /* $NetBSD: nlist_elf32.c,v 1.39 2016/02/26 17:12:53 christos Exp $ */
2
3 /*
4 * Copyright (c) 1996 Christopher G. Demetriou
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 for the
18 * NetBSD Project. See http://www.NetBSD.org/ for
19 * information about NetBSD.
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 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
35 */
36
37 #include <sys/cdefs.h>
38 #if defined(LIBC_SCCS) && !defined(lint)
39 __RCSID("$NetBSD: nlist_elf32.c,v 1.39 2016/02/26 17:12:53 christos Exp $");
40 #endif /* LIBC_SCCS and not lint */
41
42 /* If not included by nlist_elf64.c, ELFSIZE won't be defined. */
43 #ifndef ELFSIZE
44 #define ELFSIZE 32
45 #endif
46
47 #include "namespace.h"
48 #include <sys/param.h>
49 #include <sys/mman.h>
50 #include <sys/stat.h>
51 #include <sys/file.h>
52 #include <sys/ioctl.h>
53
54 #include <assert.h>
55 #include <errno.h>
56 #include <stdio.h>
57 #include <string.h>
58 #include <unistd.h>
59 #include <nlist.h>
60
61 #include "nlist_private.h"
62 #if defined(NLIST_ELF32) || defined(NLIST_ELF64)
63 #include <sys/exec_elf.h>
64 #endif
65
66 #include <sys/ksyms.h> /* after sys/exec_elf.h */
67
68 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
69 (defined(NLIST_ELF64) && (ELFSIZE == 64))
70
71 /* No need to check for off < 0 because it is unsigned */
72 #define check(off, size) (off + size > mappedsize)
73 #define BAD goto out
74 #define BADUNMAP goto unmap
75
76 int
ELFNAMEEND(__fdnlist)77 ELFNAMEEND(__fdnlist)(int fd, struct nlist *list)
78 {
79 struct stat st;
80 Elf_Ehdr ehdr;
81 #if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
82 #if (ELFSIZE == 32)
83 Elf32_Half nshdr;
84 #elif (ELFSIZE == 64)
85 Elf64_Word nshdr;
86 #endif
87 /* Only support 64+32 mode on LP64 and those that have defined */
88 /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
89 Elf_Ehdr *ehdrp;
90 Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
91 Elf_Sym *symp;
92 Elf_Off shdr_off;
93 Elf_Word shdr_size;
94 struct nlist *p;
95 char *mappedfile, *strtab;
96 size_t mappedsize, nsyms;
97 int nent;
98 #endif
99 int rv;
100 size_t i;
101
102 _DIAGASSERT(fd != -1);
103 _DIAGASSERT(list != NULL);
104
105 rv = -1;
106
107 /*
108 * If we can't fstat() the file, something bad is going on.
109 */
110 if (fstat(fd, &st) < 0)
111 BAD;
112
113 /*
114 * Map the file in its entirety.
115 */
116 if ((uintmax_t)st.st_size > (uintmax_t)SIZE_T_MAX) {
117 errno = EFBIG;
118 BAD;
119 }
120
121 /*
122 * Read the elf header of the file.
123 */
124 if ((ssize_t)(i = pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0)) == -1)
125 BAD;
126
127 /*
128 * Check that the elf header is correct.
129 */
130 if (i != sizeof(Elf_Ehdr))
131 BAD;
132 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
133 ehdr.e_ident[EI_CLASS] != ELFCLASS)
134 BAD;
135
136 switch (ehdr.e_machine) {
137 ELFDEFNNAME(MACHDEP_ID_CASES)
138
139 default:
140 BAD;
141 }
142 #if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
143 symshdrp = symstrshdrp = NULL;
144
145 /* Only support 64+32 mode on LP64 and those that have defined */
146 /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
147 if (S_ISCHR(st.st_mode)) {
148 const char *nlistname;
149 Elf_Sym sym;
150
151 /*
152 * Character device; assume /dev/ksyms.
153 */
154 nent = 0;
155 for (p = list; !ISLAST(p); ++p) {
156 struct ksyms_gsymbol kg;
157 int error;
158
159 p->n_other = 0;
160 p->n_desc = 0;
161 nlistname = N_NAME(p);
162 if (*nlistname == '_')
163 nlistname++;
164
165 memset(&kg, 0, sizeof(kg));
166 kg.kg_name = nlistname;
167 #ifdef OKIOCGSYMBOL
168 struct ksyms_ogsymbol okg;
169 error = ioctl(fd, KIOCGSYMBOL, &kg);
170 if (error == 0) {
171 sym = kg.kg_sym;
172 } else if (error && errno == ENOTTY) {
173 memset(&okg, 0, sizeof(okg));
174 okg.kg_name = nlistname;
175 okg.kg_sym = &sym;
176 error = ioctl(fd, OKIOCGSYMBOL, &okg);
177 }
178 #else
179 kg.kg_sym = &sym;
180 error = ioctl(fd, KIOCGSYMBOL, &kg);
181 #endif
182 if (error == 0
183 #if !defined(_LP64) && ELFSIZE == 64
184 #if __mips__
185 && (intptr_t)sym.st_value == (intmax_t)sym.st_value
186 #else
187 && (uintptr_t)sym.st_value == sym.st_value
188 #endif
189 #endif
190 && /*CONSTCOND*/1) {
191 p->n_value = (uintptr_t)sym.st_value;
192 switch (ELF_ST_TYPE(sym.st_info)) {
193 case STT_NOTYPE:
194 p->n_type = N_UNDF;
195 break;
196 case STT_COMMON:
197 case STT_OBJECT:
198 p->n_type = N_DATA;
199 break;
200 case STT_FUNC:
201 p->n_type = N_TEXT;
202 break;
203 case STT_FILE:
204 p->n_type = N_FN;
205 break;
206 default:
207 p->n_type = 0;
208 /* catch other enumerations for gcc */
209 break;
210 }
211 if (ELF_ST_BIND(sym.st_info) != STB_LOCAL)
212 p->n_type |= N_EXT;
213 } else {
214 nent++;
215 p->n_value = 0;
216 p->n_type = 0;
217 }
218 }
219 return nent;
220 }
221
222 mappedsize = (size_t)st.st_size;
223 mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
224 fd, (off_t)0);
225 if (mappedfile == (char *)-1)
226 BAD;
227
228 /*
229 * Make sure we can access the executable's header
230 * directly, and make sure the recognize the executable
231 * as an ELF binary.
232 */
233 if (check(0, sizeof *ehdrp))
234 BADUNMAP;
235 ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0];
236
237 /*
238 * Find the symbol list and string table.
239 */
240 nshdr = ehdrp->e_shnum;
241 shdr_off = ehdrp->e_shoff;
242 shdr_size = ehdrp->e_shentsize * nshdr;
243
244 if (check(shdr_off, shdr_size) ||
245 (sizeof *shdrp != ehdrp->e_shentsize))
246 BADUNMAP;
247 shdrp = (void *)&mappedfile[(size_t)shdr_off];
248
249 for (i = 0; i < nshdr; i++) {
250 if (shdrp[i].sh_type == SHT_SYMTAB) {
251 symshdrp = &shdrp[i];
252 symstrshdrp = &shdrp[shdrp[i].sh_link];
253 }
254 }
255
256 /* Make sure we're not stripped. */
257 if (symshdrp == NULL || symshdrp->sh_offset == 0)
258 BADUNMAP;
259
260 /* Make sure the symbols and strings are safely mapped. */
261 if (check(symshdrp->sh_offset, symshdrp->sh_size))
262 BADUNMAP;
263 if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
264 BADUNMAP;
265
266 symp = (void *)&mappedfile[(size_t)symshdrp->sh_offset];
267 nsyms = (size_t)(symshdrp->sh_size / sizeof(*symp));
268 strtab = &mappedfile[(size_t)symstrshdrp->sh_offset];
269
270 /*
271 * Clean out any left-over information for all valid entries.
272 * Type and value are defined to be 0 if not found; historical
273 * versions cleared other and desc as well.
274 *
275 * XXX Clearing anything other than n_type and n_value violates
276 * the semantics given in the man page.
277 */
278 nent = 0;
279 for (p = list; !ISLAST(p); ++p) {
280 p->n_type = 0;
281 p->n_other = 0;
282 p->n_desc = 0;
283 p->n_value = 0;
284 ++nent;
285 }
286
287 for (i = 0; i < nsyms; i++) {
288 for (p = list; !ISLAST(p); ++p) {
289 const char *nlistname;
290 char *symtabname;
291
292 /* This may be incorrect */
293 nlistname = N_NAME(p);
294 if (*nlistname == '_')
295 nlistname++;
296
297 symtabname = &strtab[symp[i].st_name];
298
299 if (!strcmp(symtabname, nlistname)) {
300 /*
301 * Translate (roughly) from ELF to nlist
302 */
303 p->n_value = (uintptr_t)symp[i].st_value;
304 switch (ELF_ST_TYPE(symp[i].st_info)) {
305 case STT_NOTYPE:
306 p->n_type = N_UNDF;
307 break;
308 case STT_OBJECT:
309 case STT_COMMON:
310 p->n_type = N_DATA;
311 break;
312 case STT_FUNC:
313 p->n_type = N_TEXT;
314 break;
315 case STT_FILE:
316 p->n_type = N_FN;
317 break;
318 default:
319 /* catch other enumerations for gcc */
320 break;
321 }
322 if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL)
323 p->n_type |= N_EXT;
324 p->n_desc = 0; /* XXX */
325 p->n_other = 0; /* XXX */
326
327 if (--nent <= 0)
328 goto done;
329 break; /* into next run of outer loop */
330 }
331 }
332 }
333
334 done:
335 rv = nent;
336 unmap:
337 munmap(mappedfile, mappedsize);
338 #endif /* _LP64 || ELFSIZE == 32 || ELF64_MACHDEP_ID */
339 out:
340 return (rv);
341 }
342
343 #endif
344