1 /*
2 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 * This product includes software developed by Christopher G. Demetriou
15 * for the NetBSD Project.
16 * 4. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #ifdef __x86_64__
32 #define ELFSIZE 64
33 #endif
34
35 #include <sys/types.h>
36 #include <sys/endian.h>
37 #include <sys/stat.h>
38
39 #include <errno.h>
40 #include <limits.h>
41 #include <stddef.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46
47 #include "extern.h"
48
49 #if (defined(NLIST_ELF64) && (ELFSIZE == 64))
50
51 #define __ELF_WORD_SIZE ELFSIZE
52 #if (ELFSIZE == 64)
53 #include <sys/elf64.h>
54 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x))
55 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x))
56 /* elf64 Elf64_Word are 32 bits */
57 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
58 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
59 #endif
60 #include <sys/elf_generic.h>
61
62 #define CONCAT(x,y) __CONCAT(x,y)
63 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x)))
64 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y))))
65 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE))
66 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x)))
67
68 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x))
69 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x))
70 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x))
71
72 struct shlayout {
73 Elf_Shdr *shdr;
74 void *bufp;
75 };
76
77 static ssize_t
xreadatoff(int fd,void * buf,off_t off,size_t size,const char * fn)78 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
79 {
80 ssize_t rv;
81
82 if (lseek(fd, off, SEEK_SET) != off) {
83 perror(fn);
84 return -1;
85 }
86 if ((size_t)(rv = read(fd, buf, size)) != size) {
87 fprintf(stderr, "%s: read error: %s\n", fn,
88 rv == -1 ? strerror(errno) : "short read");
89 return -1;
90 }
91 return size;
92 }
93
94 static ssize_t
xwriteatoff(int fd,void * buf,off_t off,size_t size,const char * fn)95 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn)
96 {
97 ssize_t rv;
98
99 if (lseek(fd, off, SEEK_SET) != off) {
100 perror(fn);
101 return -1;
102 }
103 if ((size_t)(rv = write(fd, buf, size)) != size) {
104 fprintf(stderr, "%s: write error: %s\n", fn,
105 rv == -1 ? strerror(errno) : "short write");
106 return -1;
107 }
108 return size;
109 }
110
111 static void *
xmalloc(size_t size,const char * fn,const char * use)112 xmalloc(size_t size, const char *fn, const char *use)
113 {
114 void *rv;
115
116 rv = malloc(size);
117 if (rv == NULL)
118 fprintf(stderr, "%s: out of memory (allocating for %s)\n",
119 fn, use);
120 return (rv);
121 }
122
123 static void *
xrealloc(void * ptr,size_t size,const char * fn,const char * use)124 xrealloc(void *ptr, size_t size, const char *fn, const char *use)
125 {
126 void *rv;
127
128 rv = realloc(ptr, size);
129 if (rv == NULL) {
130 free(ptr);
131 fprintf(stderr, "%s: out of memory (reallocating for %s)\n",
132 fn, use);
133 }
134 return (rv);
135 }
136
137 int
ELFNAMEEND(check)138 ELFNAMEEND(check)(int fd, const char *fn)
139 {
140 Elf_Ehdr eh;
141 struct stat sb;
142 unsigned char data;
143
144 /*
145 * Check the header to maek sure it's an ELF file (of the
146 * appropriate size).
147 */
148 if (fstat(fd, &sb) == -1)
149 return 0;
150 if (sb.st_size < (off_t)(sizeof eh))
151 return 0;
152 if (read(fd, &eh, sizeof eh) != sizeof eh)
153 return 0;
154
155 if (IS_ELF(eh) == 0)
156 return 0;
157
158 data = eh.e_ident[EI_DATA];
159
160 switch (xe16toh(eh.e_machine)) {
161 case EM_386: break;
162 case EM_ALPHA: break;
163 #ifndef EM_AARCH64
164 #define EM_AARCH64 183
165 #endif
166 case EM_AARCH64: break;
167 #ifndef EM_ARM
168 #define EM_ARM 40
169 #endif
170 case EM_ARM: break;
171 #ifndef EM_MIPS
172 #define EM_MIPS 8
173 #endif
174 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */
175 #define EM_MIPS_RS4_BE 10
176 #endif
177 case EM_MIPS: break;
178 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break;
179 #ifndef EM_PPC
180 #define EM_PPC 20
181 #endif
182 case EM_PPC: break;
183 #ifndef EM_PPC64
184 #define EM_PPC64 21
185 #endif
186 case EM_PPC64: break;
187 #ifndef EM_SPARCV9
188 #define EM_SPARCV9 43
189 #endif
190 case EM_SPARCV9: break;
191 #ifndef EM_X86_64
192 #define EM_X86_64 62
193 #endif
194 case EM_X86_64: break;
195 /* ELFDEFNNAME(MACHDEP_ID_CASES) */
196
197 default:
198 return 0;
199 }
200
201 return 1;
202 }
203
204 /*
205 * This function 'hides' (some of) ELF executable file's symbols.
206 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>".
207 * Symbols in the global keep list, or which are marked as being undefined,
208 * are left alone.
209 *
210 * An old version of this code shuffled various tables around, turning
211 * global symbols to be hidden into local symbols. That lost on the
212 * mips, because CALL16 relocs must reference global symbols, and, if
213 * those symbols were being hidden, they were no longer global.
214 *
215 * The new renaming behaviour doesn't take global symbols out of the
216 * namespace. However, it's ... unlikely that there will ever be
217 * any collisions in practice because of the new method.
218 */
219 int
ELFNAMEEND(hide)220 ELFNAMEEND(hide)(int fd, const char *fn)
221 {
222 Elf_Ehdr ehdr;
223 struct shlayout *layoutp = NULL;
224 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr;
225 Elf_Shdr shdrshdr;
226 Elf_Sym *symtabp = NULL;
227 char *shstrtabp = NULL, *strtabp = NULL;
228 Elf_Size nsyms, ewi;
229 Elf_Off off;
230 ssize_t shdrsize;
231 int rv, i, weird, l, m, r, strtabidx;
232 size_t nstrtab_size, nstrtab_nextoff, fn_size, size;
233 char *nstrtabp = NULL;
234 unsigned char data;
235 const char *weirdreason = NULL;
236 void *buf;
237 Elf_Half shnum;
238
239 rv = 0;
240 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
241 goto bad;
242
243 data = ehdr.e_ident[EI_DATA];
244 shnum = xe16toh(ehdr.e_shnum);
245
246 shdrsize = shnum * xe16toh(ehdr.e_shentsize);
247 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL)
248 goto bad;
249 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) !=
250 shdrsize)
251 goto bad;
252
253 symtabshdr = strtabshdr = shstrtabshdr = NULL;
254 weird = 0;
255 for (i = 0; i < shnum; i++) {
256 switch (xe32toh(shdrp[i].sh_type)) {
257 case SHT_SYMTAB:
258 if (symtabshdr != NULL) {
259 weird = 1;
260 weirdreason = "multiple symbol tables";
261 }
262 symtabshdr = &shdrp[i];
263 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)];
264 break;
265 case SHT_STRTAB:
266 if (i == xe16toh(ehdr.e_shstrndx))
267 shstrtabshdr = &shdrp[i];
268 break;
269 }
270 }
271 if (symtabshdr == NULL)
272 goto out;
273 if (strtabshdr == NULL) {
274 weird = 1;
275 weirdreason = "string table does not exist";
276 }
277 if (shstrtabshdr == NULL) {
278 weird = 1;
279 weirdreason = "section header string table does not exist";
280 }
281 if (weirdreason == NULL)
282 weirdreason = "unsupported";
283 if (weird) {
284 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason);
285 goto bad;
286 }
287
288 /*
289 * sort section layout table by offset
290 */
291 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout),
292 fn, "layout table");
293 if (layoutp == NULL)
294 goto bad;
295
296 /* add a pseudo entry to represent the section header table */
297 shdrshdr.sh_offset = ehdr.e_shoff;
298 shdrshdr.sh_size = htoxew(shdrsize);
299 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8);
300 layoutp[shnum].shdr = &shdrshdr;
301
302 /* insert and sort normal section headers */
303 for (i = shnum; i-- != 0;) {
304 l = i + 1;
305 r = shnum;
306 while (l <= r) {
307 m = ( l + r) / 2;
308 if (xewtoh(shdrp[i].sh_offset) >
309 xewtoh(layoutp[m].shdr->sh_offset))
310 l = m + 1;
311 else
312 r = m - 1;
313 }
314
315 if (r != i) {
316 memmove(&layoutp[i], &layoutp[i + 1],
317 sizeof(struct shlayout) * (r - i));
318 }
319
320 layoutp[r].shdr = &shdrp[i];
321 layoutp[r].bufp = NULL;
322 }
323 ++shnum;
324
325 /*
326 * load up everything we need
327 */
328
329 /* load section string table for debug use */
330 if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn,
331 "section string table")) == NULL)
332 goto bad;
333 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset),
334 xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size))
335 goto bad;
336
337 /* we need symtab, strtab, and everything behind strtab */
338 strtabidx = INT_MAX;
339 for (i = 0; i < shnum; i++) {
340 if (layoutp[i].shdr == &shdrshdr) {
341 /* not load section header again */
342 layoutp[i].bufp = shdrp;
343 continue;
344 }
345 if (layoutp[i].shdr == shstrtabshdr) {
346 /* not load section string table again */
347 layoutp[i].bufp = shstrtabp;
348 continue;
349 }
350
351 if (layoutp[i].shdr == strtabshdr)
352 strtabidx = i;
353 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) {
354 off = xewtoh(layoutp[i].shdr->sh_offset);
355 size = xewtoh(layoutp[i].shdr->sh_size);
356 layoutp[i].bufp = xmalloc(size, fn,
357 shstrtabp + xewtoh(layoutp[i].shdr->sh_name));
358 if (layoutp[i].bufp == NULL)
359 goto bad;
360 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) !=
361 size)
362 goto bad;
363
364 /* set symbol table and string table */
365 if (layoutp[i].shdr == symtabshdr)
366 symtabp = layoutp[i].bufp;
367 else if (layoutp[i].shdr == strtabshdr)
368 strtabp = layoutp[i].bufp;
369 }
370 }
371
372 nstrtab_size = 256;
373 nstrtabp = xmalloc(nstrtab_size, fn, "new string table");
374 if (nstrtabp == NULL)
375 goto bad;
376 nstrtab_nextoff = 0;
377
378 fn_size = strlen(fn);
379
380 /* Prepare data structures for symbol movement. */
381 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize);
382
383 /* move symbols, making them local */
384 for (ewi = 0; ewi < nsyms; ewi++) {
385 Elf_Sym *sp = &symtabp[ewi];
386 const char *symname = strtabp + xe32toh(sp->st_name);
387 size_t newent_len;
388 /*
389 * make sure there's size for the next entry, even if it's
390 * as large as it can be.
391 *
392 * "_$$hide$$ <filename> <symname><NUL>" ->
393 * 9 + 3 + sizes of fn and sym name
394 */
395 while ((nstrtab_size - nstrtab_nextoff) <
396 strlen(symname) + fn_size + 12) {
397 nstrtab_size *= 2;
398 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn,
399 "new string table");
400 if (nstrtabp == NULL)
401 goto bad;
402 }
403
404 sp->st_name = htowew(nstrtab_nextoff);
405
406 /* if it's a keeper or is undefined, don't rename it. */
407 if (in_keep_list(symname) ||
408 (xe16toh(sp->st_shndx) == SHN_UNDEF)) {
409 newent_len = sprintf(nstrtabp + nstrtab_nextoff,
410 "%s", symname) + 1;
411 } else {
412 newent_len = sprintf(nstrtabp + nstrtab_nextoff,
413 "_$$hide$$ %s %s", fn, symname) + 1;
414 }
415 nstrtab_nextoff += newent_len;
416 }
417 strtabshdr->sh_size = htoxew(nstrtab_nextoff);
418
419 /*
420 * update section header table in ascending order of offset
421 */
422 for (i = strtabidx + 1; i < shnum; i++) {
423 Elf_Off off, align;
424 off = xewtoh(layoutp[i - 1].shdr->sh_offset) +
425 xewtoh(layoutp[i - 1].shdr->sh_size);
426 align = xewtoh(layoutp[i].shdr->sh_addralign);
427 off = (off + (align - 1)) & ~(align - 1);
428 layoutp[i].shdr->sh_offset = htoxew(off);
429 }
430
431 /*
432 * write data to the file in descending order of offset
433 */
434 for (i = shnum; i-- != 0;) {
435 if (layoutp[i].shdr == strtabshdr) {
436 /* new string table */
437 buf = nstrtabp;
438 } else
439 buf = layoutp[i].bufp;
440
441 if (layoutp[i].shdr == &shdrshdr ||
442 layoutp[i].shdr == symtabshdr || i >= strtabidx) {
443 if (buf == NULL)
444 goto bad;
445
446 /*
447 * update the offset of section header table in elf
448 * header if needed.
449 */
450 if (layoutp[i].shdr == &shdrshdr &&
451 ehdr.e_shoff != shdrshdr.sh_offset) {
452 ehdr.e_shoff = shdrshdr.sh_offset;
453 off = offsetof(Elf_Ehdr, e_shoff);
454 size = sizeof(Elf_Off);
455 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size,
456 fn) != size)
457 goto bad;
458 }
459
460 off = xewtoh(layoutp[i].shdr->sh_offset);
461 size = xewtoh(layoutp[i].shdr->sh_size);
462 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size)
463 goto bad;
464 }
465 }
466
467 out:
468 if (layoutp != NULL) {
469 for (i = 0; i < shnum; i++) {
470 if (layoutp[i].bufp != NULL)
471 free(layoutp[i].bufp);
472 }
473 free(layoutp);
474 }
475 free(nstrtabp);
476 return (rv);
477
478 bad:
479 rv = 1;
480 goto out;
481 }
482
483 #endif /* include this size of ELF */
484