1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 2000, Boris Popov
5 * Copyright (c) 1998-2000 Doug Rabson
6 * Copyright (c) 2004 Peter Wemm
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by Boris Popov.
20 * 4. Neither the name of the author nor the names of any co-contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #include <sys/param.h>
38
39 #include <err.h>
40 #include <errno.h>
41 #include <gelf.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45
46 #include "ef.h"
47
48 typedef struct {
49 GElf_Addr addr;
50 GElf_Off offset;
51 GElf_Off size;
52 int flags;
53 int sec; /* Original section */
54 char *name;
55 } Elf_progent;
56
57 typedef struct {
58 GElf_Rel *rel;
59 long nrel;
60 int sec;
61 } Elf_relent;
62
63 typedef struct {
64 GElf_Rela *rela;
65 long nrela;
66 int sec;
67 } Elf_relaent;
68
69 struct ef_file {
70 char *ef_name;
71 struct elf_file *ef_efile;
72
73 Elf_progent *progtab;
74 int nprogtab;
75
76 Elf_relaent *relatab;
77 int nrela;
78
79 Elf_relent *reltab;
80 int nrel;
81
82 GElf_Sym *ddbsymtab; /* The symbol table we are using */
83 size_t ddbsymcnt; /* Number of symbols */
84 caddr_t ddbstrtab; /* String table */
85 long ddbstrcnt; /* number of bytes in string table */
86
87 caddr_t shstrtab; /* Section name string table */
88 long shstrcnt; /* number of bytes in string table */
89
90 int ef_verbose;
91 };
92
93 static void ef_obj_close(elf_file_t ef);
94
95 static int ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address,
96 size_t len, void *dest);
97 static int ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address,
98 size_t len, char *dest);
99
100 static GElf_Addr ef_obj_symaddr(elf_file_t ef, GElf_Size symidx);
101 static int ef_obj_lookup_set(elf_file_t ef, const char *name,
102 GElf_Addr *startp, GElf_Addr *stopp, long *countp);
103 static int ef_obj_lookup_symbol(elf_file_t ef, const char *name,
104 GElf_Sym **sym);
105
106 static struct elf_file_ops ef_obj_file_ops = {
107 .close = ef_obj_close,
108 .seg_read_rel = ef_obj_seg_read_rel,
109 .seg_read_string = ef_obj_seg_read_string,
110 .symaddr = ef_obj_symaddr,
111 .lookup_set = ef_obj_lookup_set,
112 };
113
114 static GElf_Off
ef_obj_get_offset(elf_file_t ef,GElf_Addr addr)115 ef_obj_get_offset(elf_file_t ef, GElf_Addr addr)
116 {
117 Elf_progent *pt;
118 int i;
119
120 for (i = 0; i < ef->nprogtab; i++) {
121 pt = &ef->progtab[i];
122 if (pt->offset == (GElf_Off)-1)
123 continue;
124 if (addr >= pt->addr && addr < pt->addr + pt->size)
125 return (pt->offset + (addr - pt->addr));
126 }
127 return (0);
128 }
129
130 static int
ef_obj_lookup_symbol(elf_file_t ef,const char * name,GElf_Sym ** sym)131 ef_obj_lookup_symbol(elf_file_t ef, const char *name, GElf_Sym **sym)
132 {
133 GElf_Sym *symp;
134 const char *strp;
135 int i;
136
137 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
138 strp = ef->ddbstrtab + symp->st_name;
139 if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
140 *sym = symp;
141 return (0);
142 }
143 }
144 return (ENOENT);
145 }
146
147 static int
ef_obj_lookup_set(elf_file_t ef,const char * name,GElf_Addr * startp,GElf_Addr * stopp,long * countp)148 ef_obj_lookup_set(elf_file_t ef, const char *name, GElf_Addr *startp,
149 GElf_Addr *stopp, long *countp)
150 {
151 int i;
152
153 for (i = 0; i < ef->nprogtab; i++) {
154 if ((strncmp(ef->progtab[i].name, "set_", 4) == 0) &&
155 strcmp(ef->progtab[i].name + 4, name) == 0) {
156 *startp = ef->progtab[i].addr;
157 *stopp = ef->progtab[i].addr + ef->progtab[i].size;
158 *countp = (*stopp - *startp) /
159 elf_pointer_size(ef->ef_efile);
160 return (0);
161 }
162 }
163 return (ESRCH);
164 }
165
166 static GElf_Addr
ef_obj_symaddr(elf_file_t ef,GElf_Size symidx)167 ef_obj_symaddr(elf_file_t ef, GElf_Size symidx)
168 {
169 const GElf_Sym *sym;
170
171 if (symidx >= ef->ddbsymcnt)
172 return (0);
173 sym = ef->ddbsymtab + symidx;
174
175 if (sym->st_shndx != SHN_UNDEF)
176 return (sym->st_value);
177 return (0);
178 }
179
180 static int
ef_obj_seg_read_rel(elf_file_t ef,GElf_Addr address,size_t len,void * dest)181 ef_obj_seg_read_rel(elf_file_t ef, GElf_Addr address, size_t len, void *dest)
182 {
183 GElf_Off secofs;
184 GElf_Rel *r;
185 GElf_Rela *a;
186 GElf_Addr secbase, dataoff;
187 int error, i, sec;
188
189 /* Find out which section contains the data. */
190 sec = -1;
191 for (i = 0; i < ef->nprogtab; i++) {
192 if (address < ef->progtab[i].addr)
193 continue;
194
195 dataoff = address - ef->progtab[i].addr;
196 if (dataoff + len > ef->progtab[i].size)
197 continue;
198
199 sec = ef->progtab[i].sec;
200 secbase = ef->progtab[i].addr;
201 secofs = ef->progtab[i].offset;
202 break;
203 }
204
205 if (sec == -1) {
206 if (ef->ef_verbose)
207 warnx("ef_obj_seg_read_rel(%s): bad address (%jx)",
208 ef->ef_name, (uintmax_t)address);
209 return (EFAULT);
210 }
211
212 if (secofs == (GElf_Off)-1) {
213 memset(dest, 0, len);
214 } else {
215 error = elf_read_raw_data(ef->ef_efile, secofs + dataoff, dest,
216 len);
217 if (error != 0)
218 return (error);
219 }
220
221 /* Now do the relocations. */
222 for (i = 0; i < ef->nrel; i++) {
223 if (ef->reltab[i].sec != sec)
224 continue;
225 for (r = ef->reltab[i].rel;
226 r < &ef->reltab[i].rel[ef->reltab[i].nrel]; r++) {
227 error = elf_reloc(ef->ef_efile, r, ELF_T_REL, secbase,
228 address, len, dest);
229 if (error != 0)
230 return (error);
231 }
232 }
233 for (i = 0; i < ef->nrela; i++) {
234 if (ef->relatab[i].sec != sec)
235 continue;
236 for (a = ef->relatab[i].rela;
237 a < &ef->relatab[i].rela[ef->relatab[i].nrela]; a++) {
238 error = elf_reloc(ef->ef_efile, a, ELF_T_RELA, secbase,
239 address, len, dest);
240 if (error != 0)
241 return (error);
242 }
243 }
244 return (0);
245 }
246
247 static int
ef_obj_seg_read_string(elf_file_t ef,GElf_Addr address,size_t len,char * dest)248 ef_obj_seg_read_string(elf_file_t ef, GElf_Addr address, size_t len, char *dest)
249 {
250 GElf_Off ofs;
251
252 ofs = ef_obj_get_offset(ef, address);
253 if (ofs == 0) {
254 if (ef->ef_verbose)
255 warnx("ef_obj_seg_read_string(%s): bad address (%jx)",
256 ef->ef_name, (uintmax_t)address);
257 return (EFAULT);
258 }
259
260 return (elf_read_raw_string(ef->ef_efile, ofs, dest, len));
261 }
262
263 int
ef_obj_open(struct elf_file * efile,int verbose)264 ef_obj_open(struct elf_file *efile, int verbose)
265 {
266 elf_file_t ef;
267 GElf_Ehdr *hdr;
268 GElf_Shdr *shdr;
269 GElf_Sym *es;
270 GElf_Addr mapbase;
271 size_t i, nshdr;
272 int error, pb, ra, rl;
273 int j, nsym, symstrindex, symtabindex;
274
275 hdr = &efile->ef_hdr;
276 if (hdr->e_type != ET_REL || hdr->e_shnum == 0 || hdr->e_shoff == 0 ||
277 hdr->e_shentsize != elf_object_size(efile, ELF_T_SHDR))
278 return (EFTYPE);
279
280 ef = calloc(1, sizeof(*ef));
281 if (ef == NULL)
282 return (errno);
283
284 efile->ef_ef = ef;
285 efile->ef_ops = &ef_obj_file_ops;
286
287 ef->ef_verbose = verbose;
288 ef->ef_name = strdup(efile->ef_filename);
289 ef->ef_efile = efile;
290
291 error = elf_read_shdrs(efile, &nshdr, &shdr);
292 if (error != 0) {
293 shdr = NULL;
294 goto out;
295 }
296
297 /* Scan the section headers for information and table sizing. */
298 nsym = 0;
299 symtabindex = -1;
300 symstrindex = -1;
301 for (i = 0; i < nshdr; i++) {
302 switch (shdr[i].sh_type) {
303 case SHT_PROGBITS:
304 case SHT_NOBITS:
305 ef->nprogtab++;
306 break;
307 case SHT_SYMTAB:
308 nsym++;
309 symtabindex = i;
310 symstrindex = shdr[i].sh_link;
311 break;
312 case SHT_REL:
313 ef->nrel++;
314 break;
315 case SHT_RELA:
316 ef->nrela++;
317 break;
318 case SHT_STRTAB:
319 break;
320 }
321 }
322
323 if (ef->nprogtab == 0) {
324 warnx("%s: file has no contents", ef->ef_name);
325 goto out;
326 }
327 if (nsym != 1) {
328 warnx("%s: file has no valid symbol table", ef->ef_name);
329 goto out;
330 }
331 if (symstrindex < 0 || symstrindex > nshdr ||
332 shdr[symstrindex].sh_type != SHT_STRTAB) {
333 warnx("%s: file has invalid symbol strings", ef->ef_name);
334 goto out;
335 }
336
337 /* Allocate space for tracking the load chunks */
338 if (ef->nprogtab != 0)
339 ef->progtab = calloc(ef->nprogtab, sizeof(*ef->progtab));
340 if (ef->nrel != 0)
341 ef->reltab = calloc(ef->nrel, sizeof(*ef->reltab));
342 if (ef->nrela != 0)
343 ef->relatab = calloc(ef->nrela, sizeof(*ef->relatab));
344 if ((ef->nprogtab != 0 && ef->progtab == NULL) ||
345 (ef->nrel != 0 && ef->reltab == NULL) ||
346 (ef->nrela != 0 && ef->relatab == NULL)) {
347 printf("malloc failed\n");
348 error = ENOMEM;
349 goto out;
350 }
351
352 if (elf_read_symbols(efile, symtabindex, &ef->ddbsymcnt,
353 &ef->ddbsymtab) != 0) {
354 printf("elf_read_symbols failed\n");
355 goto out;
356 }
357
358 if (elf_read_string_table(efile, &shdr[symstrindex], &ef->ddbstrcnt,
359 &ef->ddbstrtab) != 0) {
360 printf("elf_read_string_table failed\n");
361 goto out;
362 }
363
364 /* Do we have a string table for the section names? */
365 if (hdr->e_shstrndx != 0 &&
366 shdr[hdr->e_shstrndx].sh_type == SHT_STRTAB) {
367 if (elf_read_string_table(efile, &shdr[hdr->e_shstrndx],
368 &ef->shstrcnt, &ef->shstrtab) != 0) {
369 printf("elf_read_string_table failed\n");
370 goto out;
371 }
372 }
373
374 /*
375 * Now allocate address space for code/data(progbits) and
376 * bss(nobits) and allocate space for and load relocs.
377 */
378 pb = 0;
379 rl = 0;
380 ra = 0;
381 mapbase = 0;
382 for (i = 0; i < nshdr; i++) {
383 switch (shdr[i].sh_type) {
384 case SHT_PROGBITS:
385 case SHT_NOBITS:
386 mapbase = roundup2(mapbase, shdr[i].sh_addralign);
387 ef->progtab[pb].addr = mapbase;
388 if (shdr[i].sh_type == SHT_PROGBITS) {
389 ef->progtab[pb].name = "<<PROGBITS>>";
390 ef->progtab[pb].offset = shdr[i].sh_offset;
391 } else {
392 ef->progtab[pb].name = "<<NOBITS>>";
393 ef->progtab[pb].offset = (GElf_Off)-1;
394 }
395 ef->progtab[pb].size = shdr[i].sh_size;
396 ef->progtab[pb].sec = i;
397 if (ef->shstrtab && shdr[i].sh_name != 0)
398 ef->progtab[pb].name =
399 ef->shstrtab + shdr[i].sh_name;
400
401 /* Update all symbol values with the offset. */
402 for (j = 0; j < ef->ddbsymcnt; j++) {
403 es = &ef->ddbsymtab[j];
404 if (es->st_shndx != i)
405 continue;
406 es->st_value += ef->progtab[pb].addr;
407 }
408 mapbase += shdr[i].sh_size;
409 pb++;
410 break;
411 case SHT_REL:
412 ef->reltab[rl].sec = shdr[i].sh_info;
413 if (elf_read_rel(efile, i, &ef->reltab[rl].nrel,
414 &ef->reltab[rl].rel) != 0) {
415 printf("elf_read_rel failed\n");
416 goto out;
417 }
418 rl++;
419 break;
420 case SHT_RELA:
421 ef->relatab[ra].sec = shdr[i].sh_info;
422 if (elf_read_rela(efile, i, &ef->relatab[ra].nrela,
423 &ef->relatab[ra].rela) != 0) {
424 printf("elf_read_rela failed\n");
425 goto out;
426 }
427 ra++;
428 break;
429 }
430 }
431 error = 0;
432 out:
433 free(shdr);
434 if (error != 0)
435 ef_obj_close(ef);
436 return (error);
437 }
438
439 static void
ef_obj_close(elf_file_t ef)440 ef_obj_close(elf_file_t ef)
441 {
442 int i;
443
444 if (ef->ef_name)
445 free(ef->ef_name);
446 if (ef->nprogtab != 0)
447 free(ef->progtab);
448 if (ef->nrel != 0) {
449 for (i = 0; i < ef->nrel; i++)
450 if (ef->reltab[i].rel != NULL)
451 free(ef->reltab[i].rel);
452 free(ef->reltab);
453 }
454 if (ef->nrela != 0) {
455 for (i = 0; i < ef->nrela; i++)
456 if (ef->relatab[i].rela != NULL)
457 free(ef->relatab[i].rela);
458 free(ef->relatab);
459 }
460 if (ef->ddbsymtab != NULL)
461 free(ef->ddbsymtab);
462 if (ef->ddbstrtab != NULL)
463 free(ef->ddbstrtab);
464 if (ef->shstrtab != NULL)
465 free(ef->shstrtab);
466 ef->ef_efile->ef_ops = NULL;
467 ef->ef_efile->ef_ef = NULL;
468 free(ef);
469 }
470